My immediate response is "of course" but perhaps I'm not clear on what you're asking. I would hope it is essential that if a man and woman are in a relationship that they were friends first or at least developed a strong friendship as they grew in the relationship - if they aren't, I might be idealistic to think that friendship is a requirement, but it seems to me that the relationship will be very tumultuous in the long term.
For me, the bigger question is can a man and woman be friends when one of the persons is married? My experience is that's a big NO. I became friends with a man at work who is married and after about 8 months he started exhibiting signs of attraction. I was hoping he'd be able to get over it so I just kind of ignored the signs for awhile. But...very disappointing. It didn't change. I definitely felt it was my responsibility to start avoiding him for both our sakes. Probably the right choice?
Not sure if that goes the other way though. I could be wrong.