Isnt Randall a bad guy?

I mean Dante, not Randall

Nope, he (Dante,) is a good guy, who does some bad things, like all people do in life. He took no pleasure in hurting his fiance, but what happened, happened. Her "settling" for Dante as it was explained in the movie was based in shallowness, she assumed because Dante wasn't as good looking or aggressive as the guys she found herself attracted to throughout her life, that he would be easy to control, and wouldn't cheat. The fact is, even nice guys want to cheat, because that's how natural selection programed men, ensuring they would pass on their genes by... passing it around basically, while it programmed women in the opposite way, because hanging on to a man is beneficial for herself, and her children from an evolutionary standpoint, to protect her and the child's life, ensuring that her genes are passed on. What he did wasn't right, but it certainly isn't even in the top ten worst things people do to other people, hence, not a bad guy.