I want to tell my friend he should get a new boyfriend, closer to his looks.
Why do you want to go so far as to tell him to find a new boyfriend?
Because it's so hard to find a boyfriend these days so I want to help him out
They can go for whoever they want. It's not up to you to tell them what to do.
He needs to get rid of his old boyfriend. He's ugly.
It is impolite to tell others who they should be with, even when meaning well. If your friend is happy, then that is all that matters, you should try being supportive of them.