Girls that string you along are good "friend candidates." They can be found at parks, nightclubs, or on tinder. These are the girls that keep responding to your texts and calls but will not meet. Just tell them it's better to be friends. Then they will want to meet. Friends that are girls are very valuable. You'd always hear guys like Mystery and Cajun saying verbatim "I have a lot of female friends, and they tell me..." The way you learn from them is to be very open about your own sexuality, the more impressive the better. As you open up girls will open up with you about hooking up with guys on tinder or at night clubs or whatever. You can really learn from women in this way. If you're slaying it and showing her pics of girls you're fucking like she was your bro, she is highly likely to start pursuing you sexually. If this occurs I would play coy and try to withstand her advances. She is so stripped of your validation she may be completely validated and be done with you if you show interest. At most you should be torn on whether or not you're interested. Do not escalate unless she's begging you for sex. Unless she sees having sex with you as the only way to get your validation it's probably not gonna happen. This is just my experience in dealing with women who had originally at least had some interest in me, but at least with me were very wishywashy. I don't know if these are wishywashy girls or that's just how it is when girls just aren't that interested. I suspect these timewasters make a habit of wasting a lot of guys time though. But even if they have low sex drive, they are still having sex on occasion. Learn from these experiences. I've also questioned if having a very openly promiscuous friend may encourage they're promiscuity.
One thing I'll add that is funny is I've had girls show me pics of guys they hook up with. And these are chicks that did not hook up with me despite courtship. Anyway, sometimes the dudes they fuck are so dorky. I'm like holy shit I'm way better looking than this guy and I have game. It's like they say "attraction is not a choice."