It's a numbers game only in so-much that you actually have to do approaches.
Beyond that it really is all down to your approach skills.
Here's reality. No woman is actually "taken" in this current world. Hypergamy is rampant. Even if she has a BF or is married, then that will not stop her if she digs you. In fact, in many cases women in relationships are easier because the dude she's with is a beta (by the very definition) because he has committed to her. Commitment is Beta, unfortunately, so when a woman says that she "has a boyfriend", whether it's true or not, it just means that she's not attracted to you.
Right, I am aware of that (to a degree, not everyone is disloyal). Most of the women who have shown interest in me were already taken. These days it is usually married women, and they are mostly interested in sex. (Back in the day I went the relationship route, thinking that's what
they wanted, lol. So naive.) I can't recall a time where I was given the boyfriend line, so that doesn't apply here.
We might just disagree on the numbers game part. Some girls aren't going to dig you no matter what, and you have to keep trying with other prospects. Just a simple fact of life. No one is going to attract everyone, whether that's friendships, dating or otherwise. Best to keep trying with anyone you find attractive -- it doesn't have to be super serious.