I've turned down countless chances to cheat on my gf because I'd never do that to her or anyone.
And I found that when I rejected any advance from someone else they got more determined, and at times it felt hard to stay faithful.
So because I'd never cheat, if I came home and found her with someone else I'm not sure what I'd do beyond throw her out and probably lose my temper altogether, taking my aggression out on him.
If I was cheating and caught her, well I'd act the same way as above, only, with much less conviction, because I know myself I'm cheating and that would dilute my feelings. Like when someone lies, you can sense the lack of conviction in their voice a lot of the time. Your emotions would be more in check but to keep the pretense of your cheating alive you'd probably throw her out or whatever but probably take her back eventually...
