as a person with 0 relationship experience, i am confusion

my dudes, i’ve always wanted to ask this ever since i read the akihiko x haruki x ugetsu arc years ago, no matter how many times i read the chapters and re watched the movie, i’ve always been left confused. like... if being with each other pained and chained you so much ( in case of akihiko x ugetsu’s relationship ), then why just.. idk.. break up?

also, i’ve always somehow fail to understand when ugetsu said , “i love akihiko, but im in love with music” ,, im like oOookay????????? idk so?? and also with the whole ugetsu keep bringing men home to shoo akihiko like why did he do that? is it necessary for him to do that in the first place? im hella confused but still sad at the same time :( idk if i dont understand this because i dont have any experience in human relationship or im just an insensitive bitch that is a complete failure at understanding human feelings lol or probably both