That gif of Harry is just,
Harry Styles is basically a player, he knows how to pull all sorts of girls and is proud in the fact that he can do so. He's popular and charming, however he has only a select few good friends - all boys, none of the opposite sex. The only girl he's ever come closest to a friendship is Madison, who aren't necessarily friends but do look out for each other and give their opinions on the hottest girls/guys to get with and who's more of a challenge, etc. He thinks Madison is hot would never go there because she is the closest female person to him and he doesn't want to ruin that.
Could Harry be friends with either Tommo or Horan? I think Harry with either of them would get along well.
Also, could Harry have hooked up (made out with, not necessarily screwed) with one of the other girls? Or maybe one of the other girls is his next conquest? I'm thinking that with Harry + Madison's storyline, Harry wants to go for one of Madison's acquaintances/friends and she helps him do it, but when he thinks he might be falling for her, the guy who actually is supposed to be with that girl gets her instead and he's heartbroken and somehow realises that he was actually having feelings for Madison and they were misplaced or something? If that makes sense.