Jeremy only cares for one thing: Sex. Even when he has a pretty good thing going with Louise, who is putting out by the way, it's this 'player' mentality of having the next notch on the bed post.
With Alison, even if Ian tells him to stay away from her HE LITERALLY DOESN'T. He tries to shoot his shot and depending on Ian, fails horribly or gets a pity fuck to try and make Ian jealous. Hell, even if we aren't with Alison, he brags and talks shit about how great it was and what not, all while Alison is simping for Ian, even when we aren't interested in that YandereSnatch.
The bottom line is this: No matter how many people try to defend the guy, which I laugh at the jumping through hoops type of logic, the dude is scum. He doesn't care about Ian or any of his bros, just the next piece of ass he can lay his pipe in. Not to mention the dude is completely pathetic in needing BOTH Ian to curb favor with Ivy about her "possible" interest in the guy, but also Lena to line up a possible pity fuck. And even then, given the guy has nothing going for him other than his dick size, with no stamina to speak of, I find it laughable that he could "satisfy" Ivy at all. Though I know most would go full 'In your face Hawkes' were that to happen. (Jokes on them I have them on ignore.)
But I digress...