I think you have kind of already slid into the LJBF zone. Besides, if a girl strung me along like this, I would have dropped her right at the "I kissed another guy" and moved on. I'd give her a short, well-reasoned, politely toned piece of my mind so she knows that those feelings of guilt she has she should definitely feel, and I would leave and go date someone else despite any apologies.
That said, I kind of accidentally dated (sounds weird, but basically, we were forced to hang out, and I seemed to slide into my old self and it went like a date) another really hot girl, but despite what I did I like my GF and have no intention of cheating on her, I just got a bit lost in the moment because I was around an HB10 who likes me a lot (she texts me almost as much as my GF sometimes) who I once had very strong feelings for, and I had to be with for 5+ hours. This girl you may have also just got lost in a moment, she has NOT seen you much, so any connection she has is minimal, and what you build is fading away as she leaves for so long. I worry about what I'll do when I'll be separated from my GF for 10 days with this other woman in a foreign country, but I know I won't cheat because I love my GF and there's a strong connection. If you feel that this girl just hasn't had the chance to build a strong connection with you, you might want to try Freezing Her Out and continue to persue her. But, I never really bothered with love triangles. They're just such a waste of time. The only love triangle I want be in is one involving me and two girls vying for me - otherwise I want nothing to do with them.