why is uke so in love with seme? I don't get it! he treats him like trash :( and he's gonn...

Idk, but when he told the seme about his history, plus the way the younger brother pretends to be nice in front of others while actually being a rapist, I kinda got the impression that the Ike likes the seme’s straightforwardness and not hiding his true face. But idk

I don't think he is, really. Attracted for sure, he always has been, but he's also understood that he was attracted to the 'alpha', he doesn't know the person. Think of it like casual sex, he understands the line, he isn't in love, their relationship is almost purely physical (even more so because it's omegaverse), and now it's a security measure too.
Also, Renjaku has already rejected him, he just hasn't gone through with it (￣∇￣")

I’d have to agree with you on that! Just to clarify, I did not mean “like” as in romantically, but rather “like” as in he finds a personality trait in another person likable (like a general type of thing). And since he “likes” the seme’s straightforward approach to things and that he doesn’t try to sugarcoat their relationship or tries to change what they are, he is comfortable in their current situation. ٩(๑❛ᴗ❛๑)۶

Lol, I was actually replying to OP, didn't even see your comment when I posted mine (⌒▽⌒)

But, on the subject now, I think that your opinion is more accurate of Hana than Renjaku. As in, Renjaku likes that Hana is so straightforward; that he says what he wants, even if he knows he might not get it (the underwear thing, the sex thing - mostly because Renjaku said that it would happen only once) I don't think Renjaku is being straightforward, per se, more like he's being preemptive. But that's just my take, we'll see sooner or later what his game is.

I agree, your description of seme's

personality is pretty accurate according to what we have seen so far, but if the relationship is pure physical and seme knows that uke is actually in his baby steps as am omega, he can be more human and treats him better (not in a way uke misunderstands for love) and talks with him and draws a clear line.
but what can we say? the story is probably running as always, they fall for each other and become mates and all we can do is nag and enjoy (￣∇￣")