Usually LJBF you can joke about sex and they laugh along.
Over the phone there's sort of a safety net, in person it's as if none of that stuff was ever said.
She sounds like she sort of loves him but feels that he's not giving her what she wants.
Definitely insecure, and someone that sounds like they're rethinking they're relationship, but it doesn't mean she's ready or wants to end it just yet.
Reducing the cockiness just a bit and increasing sincerity just a tiny bit, might get the answer you're looking for.
Plus with you having a girlfriend, she's holding back. She sounds relationship oriented for now, prob. lost her virginity to the guy and by 21 she could be wild party girl. For all you know he might be looking elsewhere and ready to dump her. If he's 19 he might propose to her if she threatens to break up with him.
He might be taking her for granted and annoyed by her. If he finds out, he might wind up challenging you in some way, or thanking you because he's into someone else. Most guys don't want "their women'' taken from them, plus there's her
social circle and family..how they feel about him. They may think he's a great guy, or they may be waiting for her to move on.
If you're ready to dump your girlfriend and take your chances, or at least not be committed to anyone so you can freely flirt and more. Just not when she's around.
Her situation would be a bad ONS.... she's too inexperienced. But this is someone that I would think about as a potential steady girlfriend. I don't know if she'd be open to something casual, prob. not at this time in her life.
One hint: she never brings the boyfriend to the coffeeshop.
I would prob. hint at ending it with the girlfriend. Not saying it in those words, but saying you're feeling things changing between you and your gf and leaving it open ended.
What you want to know is if she's LJBF or LTR.