When Faith flirts with vampires, lets them kiss her neck and pinch her nipples, Buffy knows Faith is playing with danger and needs Buffy to trust her. So Buffy nurses Faith's wounds after she's danced too close to the edge, and says nothing.
Every time, Buffy knows there will be a next time, and a time after that. Faith will come home bleeding, drunk, high, and Buffy will be there. Buffy thinks that someday, she and Faith will both have the strength to move on. Faith seems bent on self-destruction, but Buffy knows that together they can learn to recover.
Buffy failed once, and she is determined not to fail again. She will help Faith, whether Faith wants her to or not. She marches up to Faith's motel room door and pounds. When Faith doesn't answer, Buffy takes a deep breath, and punches the door down. Faith is in bed with someone, but Buffy ignores him. She strides into the room and grabs Faith, who protests incoherently. She shoves Faith under the shower and holds Faith there the shower until Faith sobers up, and then dresses her. Faith's companion is gone by the time Buffy is finished helping her friend.
Faith hasn't spoken to Buffy in three months, since Buffy interrupted her in the motel. Buffy keeps trying, spends endless hours sparring with Faith, going out dancing, always looks to Faith first when it's time to make a decision. Faith, for her part, comes home with Buffy every night, and if she leaves again to find someone else, she's always home by morning.
Buffy knows she has given up too soon before, but this time is different. This time, if she gives up on Faith, she will be giving up on herself as well, and she can't let that happen.
Buffy knows that Faith can do as good a job Slaying as she can, but Faith doesn't agree. Faith defers to Buffy in all things, lets Buffy take the lead in fights, doesn't speak up in meetings. So Buffy lets herself get injured in the middle of a battle for the soul of a town, tells Faith, "I trust you," and passes out. Faith is torn between helping Buffy and saving Zurich, and in the end, the Swiss throw her a parade for defeating evil on their behalf. Buffy doesn't stop smiling at Faith for entire four mile parade route.
It's Valentine's Day, and Buffy wants to buy everything. She wants to plan a romantic dinner, and buy more flowers than will fit in a single hotel room, and an expensive necklace, and a dress, and lingerie. But she won't; Faith doesn't have money to reciprocate. Buffy will buy a ring made of silver with a cross on it, and whittle her girlfriend a stake. She'll make a picnic instead of the expensive dinner, and her bedroom will have to suffice rather than a hotel. A single lily is as many flowers as Faith will accept.
It'll still be perfect.
Faith knows that she can have Buffy whenever she wants, but for the first time in her life, she is beginning to understand the appeal of anticipation, of expectation. She is waiting at home for Buffy to return from a light patrol, and while she waits, she makes dinner and sets the table. Faith spent the morning dusting a nest, but this evening is for her and Buffy.
When Buffy arrives home, Faith gives her a grin, and a soft kiss, and asks about her day. Buffy grinds against Faith, but Faith steps away, and Buffy's annoyance makes her smile.
Buffy lost faith when she came back from Heaven; she was alone, and in pain, and nothing made sense. Buffy lost Faith four years before that, in an alley with heated words; she was scared, and defensive, and overwhelmed.
After all the things that she has faced over the years, Buffy has never known what to believe. Buffy never thought she'd make it to 25, but here she is, and she has a lover, and a dog, and a nice house. She has a sister she adores and a Watcher she shares. Now, Buffy believes in Faith above all else.