Does she like me or just want extra attention?

So this girl and i have become close this year and we're almost always flirty. I notice her teasing me, poking fun at my past relationships, inquiring about my past relationships, being excited during conversation, laughing at my jokes that aren't even funny, playfully hitting me, trying to get my attention, and trying to catch my gaze. I think for sure this girl has some interest in me but the problem is that she has a boyfriend. The crazy thing is this girl is not someone who you'd call a whore. She has values and she is one of those people who values love, and sex after marriage. What's crazy is her and her boyfriend have been off and on in long spurts for like 3 years, but in the most recent spout whenever she mentions her boyfriend she is usually not super excited, just sorta whatever. She cares for her boyfriend obviously, but she always mentions things like, me and bob never talk anymore (sarcastically), or me and bob never touch (sarcastically). What I'm confused about is whether that's just her complaining about her boyfriends lacks, or an invitation for me to do better if her and her boyfriend were to break up. She obviously has shown some interest in me but i'm not sure if i'm just supplying her the extra attention her boyfriend doesn't give, or if she's genuinely interested. I'm not going to try to break them up but i guess i don't really know what to do. If she was a whore i'd drop her no problem but that's what makes it wierd. I can't tell if shes just playing games with me and having a little crave for attention, if i'm a backup plan, or if she likes me but feels a great attachment to her boyfriend and wouldn't break up with him unless he did it. In the past the boyfriend has always been the one to break the relationship off, so I'm wondering if it's like hard for her to break something off when there so close, or if she just feels safe in that relationship idk. Be honest, and just let me know what you think i should do.