Tread carefully my friend! There are a lot of unknowns in dating a married person. Maybe they have an open relationship and it's ok with both parties and then again, maybe not. Read the newspaper. There are always stories of someone getting shot, stabbed or beaten cause they got caught messing with someones wife/husband. When peoples emotions are involved it's hard to say what will happen. Use common sense. Do not allow your emotions to over rule your common sense.