It only becomes a problem when coupled with a bad case of oneitis. When you are obsessing over a girl and then try to use the friend zone to capitalize on her trust for sex or a relationship, and you're only out for that one girl.. that's when it's a problem for you.

I'm a firm believer that guys can't have girl friends they don't want to fuck. Bottom line, I want to fuck all my girl friends. That doesn't mean they want to fuck me, or that it is a good idea for us to fuck. What it does mean is that I'm not focused on just one of them. And that allows me to have a couple things:

Many healthy relationships with people who happen to be girls and are awesome people nonetheless.

Awesome wingmen, all the time. I swear, women and gay men make the best wingmen because it creates instant trust in your potential interest.

Sometimes, SOMETIMES, the girl-jealousy effect works in my favor and I end up having a sexual relationship with my girl friends because they've hooked me up with their girl friends and, well, girls talk.

These are all great reasons to be mutual friends with a girl. It's not that you can't be friends with girls, it's that you can't be friends with girls and then couple that with oneitis. They need to see that you are interested in every girl BUT them. Of course all the normal rules of PUA are still in play. Don't be a doormat, etc.

I hope this helps some of you that get stuck in the perpetual friend zone.