Replying to Next time let me know you're married before I kiss you. Thanks.

So I'm at this big party at my friends house dancing with this cute girl, and we end up kissing, and yes, my friend then tells me that she is married. So I ask her and she says its true, and that they're in an "open relationship". So I split. Sorry but that's not how I roll, I can maybe understand an open relationship, but not one when you're married. Anyone else agree with me that marriage is something you don't mess around with? Or do you think im a moron and shouldnt have left her?