i desperately need advice.

there’s this guy that i like. he’s a friend. however, he’s not single. he’s been with a girl for about 2 to 3 years and it seems pretty serious.

the thing is their relationship is quite toxic. the girl would “break up” with him, ignore his messages, beg him to accept her back, basically mentally abusing him. he doesn’t seem happy anymore.

how do i make him like me?