You're assuming a lot of things.
How do you know the girls are actually dating them?
Do you even know if they're friends, or if the guys just went up to the girls?
Maybe these guys are the girls 'gay best friends'.
Maybe these guys don't have much to offer in the masculine department, but they treat the girls like queens.
Why don't you go up to a pretty girl and talk to her? The difference between you and those goofs are that the latter went up the girls instead of merely lusting from afar. If you were manly and had masculine features, you wouldn't be afraid to go up to those girls.
Often, it's the goofy guys who end up with the cute chicks because they're too stupid to worry about being rejected.
There's nothing inherently feminine about long hair. Cavemen didn't cut their hair. It's very recent in human history for men to cut their hair. Girls secretly gush over nice, long hair on guys. It serves the same purpose for men just as it does for women. If women see that you have nice, healthy and thick (non balding) hair, it shows them that you're healthy and virile. It's a very primitive instinct. Ever wonder why men spend millions of dollars to regrow and darken their hair?
Also, a lot more bisexual girls? When did this happen? Funny how the vast majority of the 'bisexual' girls only date guys. Has nothing to do with the masculinity of men, and more about trends.