ngl what did u expect haha, i actually think the lack of personal development on Momo's side is in line with canon highschooler events. Pretty realistic if im looking at it rn.
Theyre highschoolers trapped in their own world and he hasnt rlly had other various experiences yet, so if his personality is already like that from a young age, it looks pretty hard to grow from esp if he's (Momo) the type to like dominating others from the start (Gin). Im not saying what Momo's doing to Gin is correct lol no its very toxic and dark.
But we have to see that as of the timeline, he has eyes only on Gin, and feels very strongly of anything that involves Gin. At this point he doesnt even seem to care about anything else, much less look inside of himself for improvements. I'd say its a good progress that he's even willing to make way and listen to Gin's wish of being able to make a life for himself outside of Momo.
I say this because as you can read from the manga, theres no significant intervention from supporting characters, especially ADULT intervention, most of the panels only focus on the two of them, their thoughts only filled with one another. Just my two cents here ;333

The hell he straight up continuously tarnish his best friend's reputation bc he is jealous and uke is the one who apologized??? Why the fuck? Imagine being utter trash and bc uke has no one else to turn to you still get him. And ppl in the comments calling you "cuties" . Eeyuck