1)Male Lead: the male character with most influence on plot.
2)Her Foil: the male character whose personality is either so much like hers or the exact opposite, causing them to clash and argue. Some examples of this pairing type include couples with one character being Tsundere (the Takahashi Couple is one subgroup of the former) or any pairing involving a Slap, Slap, Kiss relationship. This one seems to be broken the most, since there's an entire opposite set of cliches dealing with couples that get along, however anytime the developers want UST in the story, this happens.
3)First Major Male Character She Talks To: Self explanitory. This omits males who are (A)Related to her, (B)Already in a relationship that doesn't disolve via a plot point, or (C)Dies and doesn't return to life. Sometimes, you can add childhood friend to that list, sometimes not (it matters whether or not he is the Victorious or UnluckyChildhood Friend). See also First Girl Wins.
If focus is male, just switch gender around (i.e. Female Lead, Female w/clashing personality, and First Female). It seems that, for the most part, 1 and 3 go hand in hand due to the fact that usually they are the same character.
Now, here are some examples that I predicted with the results. Two female focuses and two male focuses, two anime, and two games...
Stahn & Rutee (Tales of Destiny): Although the first female Stahn meets is Chelsea, she seems a little too young for him. Besides, she's got a crush on Garr. And Mary was married. So the technical First Female is Rutee, who is also the Female Lead. And boy, do they fight in the game. She teases him endlessly, and he yells at her for her greedy personality. But when they get to know each other, they become friends who joke around with one another. After the game, they get married and have a son named Kyle. Even after Stahn is killed in battle prior to the sequel, she still has strong feelings for him (and gets pretty depressed, she doesn't even like talking about what happened and there's this one scene where she speaks alone at night to him looking for advice on what to do about their son's rebelliousness). However, that timeline was actually an altered one and after Kyle goes on his adventure to save time, Stahn's death is erased and they get to live happily as a family.
Interesting to note, that while she originally wasn't the first girl he met in actuality, when the game was remade Rutee stowed away on the Draconis as well, and ran into Stahn before he made his escape with Dymlos. Meaning, she was upgraded from the first technical female to the first female, period.
Bit & Leena (Zoids: NC/0): When Bit encounters his future team mates for the first time in Episode 1, the only girl among them is Leena. That makes her not only the First Female, but Main Female. Over time, they fight one another all of the time, whether it be over him walking in on her shower, or cookies. Ok, so Leena fights with everyone, but only Bit fights back, and the fighting must be mutual for it to work. Besides, he's the main focus. It is never directly stated that they love one another, but it is never stated that either of them loves someone else either.
Virginia & Jet (Wild ARMs 3): Although Virginia met the whole rest of the cast at once, Jet was the one to make the most influence on her. He's always saving her life for Pete's sake. If I had to pick a Male Lead, it would be him, because he is the one whose existance is key to saving Filgaia from certain devices the Prophets activate, due to him being the Filgaia Sample. Her quest for justice and longing for company, and his love of treasure and solitude cause many arguments between the duo. As do her affection for memories vs. his not caring about them. Again, it is not directly said that they get together, but she does give him a hug when she wakes up after Filgaia is revived in the end LOL.
Lina & Gourry (Slayers): Again, Gourry is both the Male Lead and First Male she sees. Even if you go by timeline, where the OAVs would be before Episode 1, he is the first major male character she meets up with (as she only talks to her clients and enemies before him). She's always yelling at him, and he fights back.
But in Slayers NEXT, it starts to show a deeper relationship. First prominent part would be episode 13, after Lina fakes her death to trick the Mazoku Kanzel. Gourry hits her on the head, and asks her to consider his feelings. You should see Lina's blush. Then, in episode 18, when Auntie Aqua asks if he is important, Lina blushes sooooo bad. It was also that episode that Gourry tells Lina, after she asks how long he wants to protect her, "I don't know, the rest of my life?" The final four episodes are what really defines the relationship. In episode 22, Gourry was kidnapped by Phibrizzo, the Hellmaster. At the start of 23, Lina wakes up from a dream about Gourry, crying. Lina never cries! Then, she screams at Phibrizzo later on to tell her where Gourry is. Episode 24 didn't hold too much, mainly because they were more intent in dealing with Sairaag's zombified inhabitants. But in 25, after Phibrizzo cracks Gourry's soul crystal, she decides to risk the whole world for his safety, summoning the Giga Slave to call on the Lord of Nightmares, saying she doesn't care what happens to her, as long as he lives. That was how she called L-Sama into her own body, her pure request. In 26 was the big one though. Gourry chases the Lord of Nightmares, trying to retrieve Lina from inside of her, even yelling "You belong with me, not inside that kiosk" (this is Gourry we're talking about, he didn't quite get the word chaos). He even let the Sword of Light go to make his way to her. Finally, when she reappears, they hug and kiss. Sadly, they don't remember and Lina throws him. But both of them do know that something important happens. Martina even seems to know, she tells Lina that much in the last two episodes.
Ok, now onto TRY. Not as much evidence as NEXT, but it was an add on series not based on the novels; or at least that's what I heard. However, when Jillas partners the team up into couples (the wrong couples so they would be unable to work at their peak efficiency and he could steal the Sword of Light) Lina was with Zel, Amelia was with Gourry, and Filia was with Xellos (even though it's a popular pairing, especially for LG and AZ fans, those two still don't get along well due to stubborness). Amelia says that "Mr. Gourry needs to go with Miss Lina." The only reason Gourry, Lina, and Zel weren't as mad was that they didn't take it seriously (Zel and Lina believed it was just a stupid tourist attraction and Gourry isn't bright). After the battle with Dark Star in Episode 14 ends in disaster, it seems that Lina is most worried about Gourry out of the team (his name is always first when she lists her missing allies). During the final battle in Episode 26, there are meaningful words spoken between the two in order to up the confidence level of the fight. Finally, during the credits (after Gourry gives Sirius the Sword of Light to take back to its world of origin), in the last scene in fact, you see them eating at a resteraunt and then walking away from the viewer together; a chicken leg in Gourry's hand. Thus, they stuck together with or without the Sword of Light, and really care.