I dont' want to rain on your parade but I have to be honest with you. By your multiple times forgiving and trying to move on after he screws you over again and again, is more an enabling behavior than anything at all. He knows he will not lose you, so what's his motivation for even trying to be different? Without him facing the real consequence, i cannot in good conscience, say that i believe with you - that it will be different. it's part of the cycle. it's the "honeymoon" phase, after being caught, the perpetrator, cheater, etc will be "good' for awhile, usually only to get past your initial anger and the threat of your wrath. When that's gone, 9/10 they go back to the old behavior having had no real consequences to face. Your "words" and "ground rules" more than likely mean nothing. I am not saying this to make you feel bad but be wise in your future.. Please be wary. Most likely it wasn't the last time.