Interesting.
My husband is an alpha male. He's very masculine and rugged. He drives a big truck, wears steel toed boots and a hard hat nearly every day, looks like the Marlboro Man, thinks George Strait is the greatest musical genius of all time, and loves big dogs. He's also very chivalrous and gallant with women, and very gentle with little children. If I ask him something like, "Which outfit do you like best on me?" or "What was your first impression of me when we met?" he will get an alarmed look on his handsome face, and say quickly, "I'm scared - it's a trap - don't ask me that!" and then flash me that killer grin of his and say something like, "Uhhhh, you're pretty?"
He's traditional and protective and would tear anyone asunder, probably with his bare hands, if he thought they meant me harm.
I say all that to lay the groundwork for my next statement - in case anyone got some idea that my husband is some sort of controlling misogynist.
He would not like - and probably would not tolerate - me having a close male friend that I spent any significant time alone with. I mean, I didn't really have any when we met, so it's not like he'd ask me to give up something in order to be with him. I've had male friends in the past, but now that I sit here and think about it - no lie - they were nearly all gay.
He didn't have any female friends when we met either. We both had that in common - several very good same sex friends and basically no friends of the opposite sex.
I have many CASUAL male friends - from work, church, etc. But my experience has been that if I allow too much familiarity, it can lead to some awkward situations.
My husband has had the same sort of experiences with women. He's outgoing, good looking, and confident, and makes good money - I have personally witnessed women basically throwing themselves at him, especially when we first started dating seriously.
Considering that we haven't had a history of many close opposite sex friendships, it would be out of character for either of us to suddenly develop one - and in my opinion it would be a red flag.
But hey, that's just us. To each his own. If other people can keep it platonic, more power to them.