You read it like this...
Track # Title (Artist)
How it relates to their relationship.
1. Glory of Love (New Found Glory)
I know this is a cover, but I like it better since it's more upbeat. The singer thinks of himself as his beloved's hero, a man who will fight for her honor always. He also feels stronger when she's near, feeling her support as well even as he protects her. Seeing her upset, especially if it was his fault, makes him sad. Well, Stahn is kind of a wannabe knight, even being told so by Leon. He supports all his friends through tough times, but especially Rutee, who is all alone in the world and has just been forced to kill her family. They do fight, and upset one another, but he well prefers her when she's happy. Not only that, but Rutee is also his support when he has an issue later on.
2. Out of the Blue (Debbie Gibson)
The singer has suddenly found love in front of her when she's never been in it before. This sudden affectionate relationship has changed her life for the better. Not only that, but she didn't even know how it felt and never thought she would find out. Rutee's original reason for recruiting Stahn was to simply make more money; she never expected to be in love with him. Because of this, she has finally been able to feel what was denied her all these years because of Kronos...affection.
3. Forgive Me (Evanescence)
The singer is asking her beloved to forgive her for saying something hurtful in an argument. She doesn't want him to leave her, but also knows that he won't do it because he loves her. Rutee lacks tact and sometimes blurts out things without thinking (i.e. in trying to cheer Stahn up, she asks if she's ever lied to him when he ignores her and he knows all too well that she has lied in the past). Also, she can be a bit of a tease. However, she never truly means to hurt him, she just loves to playfully banter with others. Stahn understands her, and will forgive when she's truly sorry.
4. You Are Loved (Josh Groban)
The singer is trying to support his sad lover because she is in pain. He knows that everyone wants to be understood and loved, and tells her that he's the one who will do that for her. Rutee was suffering throughout a lot of the game, but Stahn was her support. The lines Don't give up, it's just the hurt that you hide. When you lost inside I...I will be there to find you seem to best fit that theme of protection; Rutee tries to hide her pain away in order to keep herself looking strong, but Stahn knows she's lost and will guide her through.
5. If That's What it Takes (Celine Dion)
The singer is promising to support the one she loves when he is going through a rough time because he was there for her when she needed it. They don't care how hard it is, they will make it together. Stahn always supported Rutee when she was down, and she did so after Ilene's death. I'd guess she'd do it again when his grandfather dies, though we don't have that scene in any game to confirm. However, their mutual love and support of one another shines through.
6. My Immortal (Evanescence)
The singer is all alone because her lover has died (well, it could have been that he left her, but the somber tone to me suggests death and Evanescence has sung a few songs about being separated by death) and she misses him. Her energy is draining because she can't just let go and forget; a part of him is still with her and he took her soul with him when he died. I think this fits the mood of Rutee after Stahn's death at Barbatos' hands before ToD II. She had just lost the one she loved more than anything else, the one who got her through losing her family. It hurt so much, that she could barely talk about him with Kyle until right before the boy left on his journey and then when he needed advice and she could finally come clean with what happened.
7. Angel Eyes (Ace of Base)
The singer knows she's not the first in his affections. However, this is the true love both of them have been seeking, their eyes are what tells her so. Stahn has so many girls that are interested in him, and he actually went on a date with Ilene before he found out Rutee was the one. All that Rutee cares about is that Stahn loves her now, that he is hers in the end. He didn't have to say the words, nor did she, but the two already knew what they wanted.
8. Accidentally In Love (Counting Crows)
Love hit the singer quite unexpectedly and now he doesn't want to leave it. He knows he can never escape her love, nor will they ever be alone anymore. Stahn surely didn't think he could fall in love with Rutee, just that he would help her out a little. Also, her attitude turned him off at first. But over time, without even asking for it, their emotions began to change and transformed into true love.
9. Bring Me to Life (Evanescence)
The singer is practically dead on the inside, lost and alone. She feels like she's without a soul, it's sleeping somewhere else, and is calling on the one she loves to awaken her. Her whole life seems to be an empty lie. Rutee lived without being true to herself for so long as she attempted to simply survive for herself and the orphans. Inside, she was lost without knowing who she really was. However, when she needed him, Stahn was there to lend a hand and awaken her.
10. I Don't Know (Celine Dion)
The singer feels she can get through any obstacles she comes across. It doesn't matter how much she is tossed about, she'll get back up and fight her way to the end. However, the one thing she doesn't think she could face is a world alone. Rutee is a fighter, plain and simple. She can kick major butt and take names and get through life without physical help. But she still needs the emotional help of Stahn. Facing life without him would be unthinkable...
11. Dreaming of You (Selena)
The song plays like a love story. A young girl is thinking and wondering whether or not a certain boy cares for her. She holds him in her dreams until she can get the courage to tell her true feelings. Eventually, he admits how he feels for her, and the two are together forever. Rutee wondered about Stahn's affections because of his constant friendly relationships with other women (can we say "unnecessary jealousy?"). Eventually, he does realize he loves her and they marry...holding an eternal bond that lasts both in his death in the alternate timeline, and in the true timeline where they are together.
12. I Wanna Love You Forever (Jessica Simpson)
The singer is finding herself falling in love, despite never wanting to in the first place. She can't explain it all, but knows she needs him in her life. Rutee is a tough and independent woman who never desired to be loved by a man. But now, she finds herself at the mercy of Stahn's kindness and affection...kindness and affection this lonely girl knows she wants more than anything else.
13. Even in Death (Evanescence)
The singer's love is dead and everyone else has accepted it. However, she knows that he's still with her, their love will always continue. After Barbatos killed Stahn, Rutee was lost and alone once more. But as shown when she talks to the night's sky about her situation with Kyle near the beginning of the game, she still can feel his presence watching over her. As the spoken quote at the end of the song goes, People die, but real love is forever.
14. No Living Without Loving You (Celine Dion)
The singer realistically looks at what life would be like without her beloved. Sure, time would keep moving just the same; it wouldn't be the end of the world. However, she wouldn't really be living without him even as the rest of the universe turns. Rutee is quite realistic in her views sometimes. When Stahn died in the altered timeline, she knew the universe wouldn't crumble away. But all the same, she had now lost the most precious thing to her and it had changed her life for the worst.
15. Strong Enough (Sheryl Crow)
The singer is dealing with issues and sometimes really can't be bothered with anything. Her man needs to understand why she's angry, why she needs to be alone, and also to have the strength to put up with it. Stahn is both a strong and understanding person. If Rutee is dealing with something she needs to work out herself, he would definitely let her do that while still offering his support.
16. I'll Be There (Escape Club)
The singer has died, and is trying to send the message that he will still be with his beloved if only she thinks of him. He will still watch over her, and wishes he could be with her in reality as well. Stahn was always in Rutee's heart when he died in the altered timeline. If he could have come back to her, he would have in a heartbeat...but eventually he could return when his death was nullified in the restored timeline.
17. Once in a Blue Moon (Sydney Forest)
The singer is apart from the one that she loves, and she is wishing to see him again. She remembers the past and knows she will wait for the day when their paths will cross. Rutee obviously missed Stahn when he left the first time, shown by her sadness at him leaving and trying to push him away. So the second time, she was probably counting the minutes until the reunion when she would once again be with Stahn. Considering Kyle's age...I'll bet it was around that time that everything with them came out in the open.