You can lie to yourself all you want about his character development but in reality it's really not that good. It was literally a 180 in one episode without any reason or explanation. A story being cut into 2 completely different stories, definitely not good writing.
The change is definitely quite sudden, but Takamadas circumstances aren't yet fully explained. Also it's not like the 180 happened in one episode nor without any explanation. Takamada started seeing Yu more as a person and developed feelings towards Yu and didn't want to hurt him anymore (f. ex. when Yu got sick Taka bought crapton of stuff and held back even tho he didn't really have a reason to) + the losing of virginity to a man was a shock since Takamada didn't think he was gay.
Taka also has still those urges as we can see in episode 107-108 so it's not like he was "cured with the power of love".
The time it happened was wayy too short and at first I thought we may get a clear explanation of wtf happened but like you said
" his circumstances aren't yet fully explained" and you know what, I don't think they'll ever be explained. I still wonder wtf happened in ch 108 because how many chs has been since it came out? exactly.
And these little examples really are not enough in order to say the man went through a good and well written development. If you ask me, I don't think anything will justify this guy's development and I hate the first story with my heart. Realize you don't want to rape someone is not maturing yall, it means you should've gone to therapy long ago, but now you know it too.
I really call it two storys because they make no sense together and yet still even if I read when's there's an update, I can't find it cute thinking about the journey this story has gone through.
Yall hate seeing ppls maturing and actually try to have a healthy relationship??? Istg this is the most well develop character, ans their traits and personality are potraid nicely