theres not a nice girl without a bf so we men always start as a third person in relations with them?

Answer 1

Starting as a third person doesn't sound like a good deal to me.
The way I see it is this: Someone who is in a relationship generally appears more attractive because they have higher confidence, more reason to look good from day to day, a bit of a happy glow about them, and so on.
Back when I was single, I wasn't considered particularly attractive. I also had a lot of sharp corners in my personality that needed a bit of friction from a close relationship to smooth them out. My social confidence was low; I was really shy, and in many situations, offputtingly awkward.
I've been married 10 years, have 2 children, and a lot more confidence as well as a broader personality and interests. Most people of all ages, even women, would now rate me as attractive.
What I'm getting at is this: If it's true that people's personalities ripen better within a relationship, then it might be in your interest to make friends with a lot of girls you don't find particularly attractive at the moment. You never know.

Answer 2

nice girls just dont come around too often.

too often guys rarely notice them because guys tend to overlook them. most nice girls are friendly and so some guys might think that they are already taken when in reality they are actually just keeping an open-mind into finding the right guy.

third person relationship if you're referring to it as a friendly relationship is ok because it lets both the boy and girl learn about each other before they actually become together.