It would be pretty hard. I know that it "could" happen, but with only having one car and me having to pick him up and take him to work, it would take some serious time management on his end to work it out.
I trust mine. Not only do I trust him, but he doesn't have time to cheat between his job, his 2 kids and his pregnant wife.
I'm not tying to be a douche, but if he wanted to cheat, he'd find the time.