What does it mean when a girl stares at you?

This is confusing me. I met this girl about two weeks ago (i'm in uni btw) and had an instant attraction to her, so naturally I started talking to her. There was definite flirting, even some touching involved. Until one of her friends casually mentioned she had a boyfriend, so I kinda backed off. IDK if she noticed or not. A couple days since then, I've kept minimal contact with her (don't have her number). Minimal contact was so that my stupid self won't get too hopeful and attached.

Anyway, since the flirting stopped, every time we're in the same general area she's always looking at me. EX: I'm going to the English building, there's a crowd of people, she looks back and her eyes lock on me... EX: In my stats class, a guy went up to ask the teacher something, she didn't look up. But I went up to ask the teacher something a couple minutes later, she stared me down until I sat back down. etc etc... and every time I catch her staring our eyes just lock. She doesn't look away until I raise an eyebrow or look away first. can anyone tell me what's going on?