Ya know....the seme is an asshole. Even if he isn't the worst of scum, he's not exactly ...

this is exactly what I thought after I finished it just now. It still hard to trust the seme I wanted him to show his love more ugh

I actually usually would feel the same as you in most works similar to this but somehow I don't feel like that in this work. I think it's because since chapter 2, the seme, Ryouhei, has already been showing signs of affection towards the uke - even rejecting having sex from that woman who sent an offer by text. For me, it didn't feel as if the seme only got to love the uke by the end of the story, it was developmental, bit by bit, these little things he did that could go unnoticed for some, and seeing this story from the seme's pov a lot helped that idea get across to me.

And btw the seme did get jealous! In chapter 2 when the uke was smiling to someone in the library, the seme got a bit angry (as noted by Yuuma afterwards)

Did he reject the lady though?
My memory isn't the best, so I could be wrong, but I remember him still sleeping around after they got "together"

And as for him getting jealous...tbh, in that scene...the way I interpreted it was that his ego was so massive, and it had been stocked oh so much by the uke's seemingly endless love that he couldn't handle such devotion and attention being directed at anyone other than him for even a moment.

Yes, he repeatedly shows signs of thinking of the uke as something more than just another bedwarmer, but that does not make him good.
He cares for him more than any other, but when you're comparing to people he never even cared for in the first place...is that really worth anything much?

Hmm, with how the story went, I don't think the seme was a jerk like how you perceived him to be. He thought about the uke a lot. If he just used Yuuma as a bedwarmer then he wouldn't have taken up too much of his brainspace to wonder about Yuuma each and every time. Remember that Ryouhei isn't originally someone who sleeps around or a playboy, he did have serious relationships in the past but he grew sick of how shallow they ended - that's why he resorted to no strings attached. Imo, if Ryouhei didn't care at all, he wouldn't notice (at all) Yuuma's efforts to not "disturb" or "ask for more" from Ryouhei. The fact that Ryouhei realized and saw all these normally unnoticeable things (for someone who doesn't care), says that he isn't someone who "doesn't care" and actually really cares. He might not be the best but I think he's a lot better than how you perceive him.