If a woman is friends only with a single available man then that means that's how she wants it. Woman can hit on men & men think to themselves "wow did she just hit on me." Women can do it very subtly. Whereas as men only know one way to hit on women & that's directly. That's why they don't always succeed. Hence slapped faces lol. I think men like a challenge so are often out of their league with some of their choices. friends only is possible but at some stage if the people are both single they fantasize about taking it further whether they have the courage to or not.
um..... I have a guy friend, but I don't talk to him or see him without my husband knowing about it...and most of the time my husband is there, and now they're friends too. It's a safeguard for our marriage.