Good question...
I think so long as he avoids being alone with someone who's interested in sleeping with him, he should be able to avoid cheating as well.
Well, if you look back to the first chapter Megumi gets in a fight with a couple guys and all things considering was hangling himself fine, and he did headbutt Souji before when he was pushing his luck before the confession. I think if anybody else tried something he'd fight them off. He just let's Souji get away with murder so it makes him look weaker than you'd think. Megumi might be weak to touch, but he doesn't let just anyone touch him. If he wasn't picky he wouldn't have been wotking so hard to avoid everybody.
would someone who over sensitive to just anyone touch , be able to stay faithful to his lover ?