then texts "I'm free that night. I do have a boyfriend but I thoroughly enjoyed our conversations if you're interested in another friend up here."

There was no mention of a boyfriend the entire night. What do you think are the chances this supposed boyfriend actually exists as opposed to her wanting plausible deniability/validation/free drinks?

What @mattyanon said. He most likely exists, but that didn't stop her from using you for free shit. Women use men for free shit all the time. In other news, water is wet.

Where is this boyfriend while she's drinking and flirting with random men on the weekends?

Probably at work.

I don't mean this to sound like red pill rage bait but that is actually what happened.

We've all been through similar.

Check it out: in addition to what matty already said about probing, this is also a good reason to escalate early and escalate fast. One drink, then kiss attempt, and getting "I have a boyfriend" is a lot better than wasting as much time, effort, etc as you did.

I tell him they seem like timewasters looking for free drinks and entertainment... My girl continues to show to be a timewaster

You nailed it. Listen to that voice next time.

but he says "he could see something longer term with his girl".

He hasn't even fucked her yet. That's retarded.

All that said I'm not upset to have a hot young girl to value tap and use as social proof

I doubt she'll be all that useful in that way. Try getting her to set you up with one of her hot friends. See how that goes. If she makes excuses, she's trying to keep you as an orbiter (this isn't necessarily conscious on her part, but rather instinct).