I think alot if it is down to age. If your a young man, sexual ideas and hormones are high. You can be friends with an ugly girl, putting it bluntly, but you eont show any intrest when you have a good looking female friend that has your intrest. As soon as you get along with a girl whos good looking, ur hormones kick in.
They say males lose sex drive and by 45 you arent that fussed about your blacklisf of numbers.
Females have a higher sex drive when 40 or more.
I have female friends, but even with a girlfriend you do need to still restrain yourself from being stupid. I have other unattractive girl mates who I do speak to and have no intentions of sleeping with or flirtimg, but they try flirting with me.
I think its all about having categories. By this I mean.. if im an 8 out of 10. If im talking to a hirl 9 or 10 out of 10, u dnt want to let go an opportunity to "tap that where as if im friends with a girl 4 out of 10, theres no attraction. However, if she thinks shes a 4 and im an 8, she wont want to miss an opportunity.
With age comes sensibility, im still 24 so lack the maturity which I can admit