Manager is right. Dude has like a static way of acting towards everyone. Childhood friend still looking for that rebound as well. Just leave them be. He deserve to be the second choice at this point.
No, no it's not. When it makes sense or is just for fun, sure, but you don't accept just to prove yourself when you have nothing to prove and there's absolutely no upside for you. Mangakas not understanding that is what makes this trope so annoying.