Is she playing mind games with subtle movements?

There's this girl that I'm extremely attracted to at school. I remember that the first time we met (or knew of each other) I was just kind of walking past her and she almost stopped what she was doing to just stare and I could tell through the corner of my vision. I noticed that her and I have this strange "eye connection" and sometimes we glance at each other and put out pretty intense glares. She's gay, but the thing is she has a girlfriend, who happens to be in one of my classes. She and her girlfriend have broken up before in the past but they've always reconciled and they seem to have been in the relationship for quite some time. I've talked to her before but our convos were always kept short and to the point, and she seems to try to avoid me and all conversation. Yet I've noticed that whenever I'm speaking and she's around she just stares at me intently and sometimes we lock eyes for a bit and then one of us breaks the contact. She gave me a cute smile once when she walked into my classroom and we locked eyes for a few seconds and it just ended. I'm not really looking to butt into the relationship at all, but I'm just curious to know whether or not she may be attracted to me physically because the connection I feel with her whenever she's present even through subtle movements is undeniable.