Most Helpful Guy
well, it depends... they might cheat on you with a girl with a better body, (although bigger but and thicker doesn't appeal to me.. ) to leave you though, would be a big change... something along the lines of... other big reasons, (fighting a lot, problems in the bedroom. etc)
Most Helpful Girl
This isn't going to happen, you're just sounding needy and insecure and that will just act as something to push him away because you're too hung up with your own personhood. Concentrating on your own faults - possibly even ones that imagined rather than real - is a downer on a relationship and he will get tired of trying to micromanage and validate your own feelings.
Give yourself some ounce of respect and believe yourself to be worth him. If you want to win at things like a successful relationship, you have to play like you're the best player.