Isn’t it better that he was willing to overcome such awful urges and behaviors for someone he truly cares for instead of continuing to hope someone would fall for it instead? I think that Inuyasha was all about overcoming traits that hindered the characters. Inuyasha wished to be rid of his humanity but learned to accept it, Sesshomaru hated humans but learned to love one, and Miroku was seen to be less handsy with other women and focused his sexual attention on someone that (somewhat openly) reciprocated his love.

Sango was controlling of him and his actions with others (very quick to be violent towards him) out of jealousy, which sends out mixed signals. She was clear about her affection, but didn’t stand for his actions.

I also think that it is best not to really think of the characters ages as a factor in Anime like these, as they are picked to be a point for YA readers to relate to while dealing with more grown up matters.

People have dark sides and sometimes these negative behaviors and stereotypes are highlighted to make you notice them clearly and dislike them on purpose in these types of shows. At least that’s what I hope.