I did end up dating one of my best friends of the opposite gender, thought that's rather a wacky story I'm not gonna share now. That said I do have quite a lot of female friends relative to male friends, for whatever reason. When I was younger (16-24) the girls I had gone out with would absolutely lose it if I even looked in the general direction of another female. I felt I had to dump any female friends I had anytime I went into a relationship.
I'm getting older now though (a whopping 29) and I would not drop any female friends I had to be with anyone. I've become of the mind that if I cannot trust my partner to be faithful, why am I in a relationship with her? And I'd expect if someone really did not trust me to keep my pants on around others (or at least, my underwear! I reserve the right to walk around half naked in my house during the summer!) that they probably should not be in a relationship with me.
I have one female friend that I chat with quite a bit on texts, and in the past it did get me some funny looks from my ex. But since I wasn't interrupting our time together to chat with her, nothing ever really came out of it. But I mean, that would have been an issue regardless of whether it's a guy friend or girl friend. It's a pretty mean thing to do to interrupt someone so you can chat with someone else on text
Which, naturally, is why I make a point of doing it with my current GF (the aforementioned best friend) to annoy her as much as possible.
opcorn:
My SO is a really flirty person in general, but since we've been in a relationship, she has kept her male friends but no longer acts flirty with them or tolerates them flirting back with her. We did have an issue with this as recently as last Saturday night when we were at a halloween party. She wore a rather revealing outfit and one of her male friends took that to mean he can touch her anywhere he wants and talk dirty with her. When she told him off the third time, he was apparently (I retreated to a dark corner out of sight at this time to regenerate my Happiness Points. Introverts and Parties are a difficult combination on my willpower) rather upset because she had allowed him to do such things in the past when she was single. So he got cut out as a friend in part because it would definitely upset me if she did not do so, but mostly because he's a pig.