Music Video, 2000s to Present. Guy works out to lose weight and get girlfriend back. Girlfriends new bf is fat. - eviltoast

MV starts out with a loser guy being dumped by his girlfriend. He is depressed but a black guy/genie in a pink tracksuit shows up and motivates him to do boxing and running.

Guy then loses weight and becomes the Singer? He goes to exes lawn and has a giant lighted sign with Sorry and pleads for her

Ex comes out with new bf who is fat.

These are definitely not the actors, but who they remind me of, black genie is Ty from unbreakable kimmy Schmidt. Guy in thin form looks like a boyband member. Fat new bf looks like Hurley from Lost