He was jealous
I've been thinking a bit about Buster's character, and why did he bother him so much that Tramp stayed with Lady?
We know that Buster hates all the dogs that have a home, but... remember that his former friend Tramp had had several girlfriends before, and in the first movie the dogs of the pound mentions that he liked those that were more refined, that is Tramp had already been in relationships with other dogs that had a home, but Buster never mentioned that it disgusted him.
So why did it bother him that Tramp was with Lady?
Besides that at some point in the movie Tramp mentions that Buster was jealous.
This leads me to think that maybe at a certain moment Buster had a crush on Lady and tried to conquer her but failed in the attempt. Then upon learning that his friend was also in love with her and that she felt the same for him, Buster was angry.
So Buster deciding that if he did not have the girl nobody would have her, so Buster deciding that if he did not have the girl, nobody would have her, he told Tramp to choose to chew on the streets with him or if Tramp went with her they would never be friends again, of course! We already know that he chose Tramp.
This would explain why Buster now has so much hatred for Tramp, not only is knowing that he lost a friend but also he stayed with the girl that Buster wanted.
Well that's it, I hope you liked this new article, I say goodbye.