My 2 cents is ... Brace yourself because I live in left field most of the time ... :-)
I think it really depends on what each individual believes to be 'right/wrong' and the circumstance that individual is in at the time.
I do not claim to be nor would I want to try to attain to be in the category of 'a moral person'. To me I could care less about all that. One thing I am is authentic. For me personally, marriage is not worth the paper it is printed on allot of times nor worth the government that makes it valid. But committment and the desire to hold up your end of that committment does have value in my 'left field' world. For me marriage and the desire to hold up your end of a committment are NOT the same thing.
I am happily committed to a non-married man. And I can see us being together until we are both farting dust. I am pretty monogomous by nature but I know many (married and single) who are not. If I was "single" I can not see me 'dating' a married man. But there are guys in my past that if they were married or single and I was single that I would probably be open to having a sexual encounter with if either him or I wanted/needed it in our lives at the time.
That's my 2 cents ...