Supposedly straight friend sending mixed signs

Hey, everyone.
I'm 25 and I'm a bisexual cis woman and I really need a little bit of advice.
I have this friend who's supposedly straight but keeps sending me mixed signs about how she feels about me. I have a big big crush on her, which she doesn't know about, but she does know I'm bi.
We've known each other for a few months now, and we're pretty close, since we study together and have a lot of things in common. I absolutely adore her, because she's so smart, so kind and so sweet!
So anyway, I've always thought she might feel something about me, because she keeps making me compliments about everything I do; she loves my accent, she says I'm charming and cute and smart, and well, you know. I know this alone means nothing, but I have never seen her treat other people the way she treats me.
Yesterday, we were at a party together (at a mutual friend's place), and it was just... Strange. First of all, we kept hugging each other all the time, which is not all that unusual, but then she started saying I was tempting her (which I was, or at least trying to). Every silly flirty joke I told was "so cute" to her.
We were drinking and hugging and then she tells me to confess, because she had something to confess to. I had NO IDEA what she was talking about. I mean, unless she wanted me to confess I had a crush on her. But other than that, I have nothing to confess to her.
This got me really confused. I asked her what she eas talking about and she was like "come on, stop playing". We were then interrupted by a friend and didn't talk about that anymore.
As we progressively got drunk, she started kissing my cheek all the time. Or my forehead. And holding my hands. And dancing with me in a really-close-to-sexual-but-not-quite way.
By that time I was sure she was going to try to kiss me eventually, but that didn't happen.
Instead, she accompanied me to my place, picking up flowers from people's windows to give me. But nothing happened because there was another friend with us.

See, I don't know what to think, because besides being supposedly straight, she has a boyfriend. Even though we're really close, I don't know him, she never even told me his name, so I'm not sure if that's true... But then, why would she lie (not just to me, but to all our friends) about it?
And if she does have a boyfriend, why is she treating me like this and telling me we should go live together in Lyon (I'm moving there in a year, to get my Master's degree)?
I'm so confused and so frustrated! But I'm really afraid to address this directly with her, or to make a move, because I don't want things between us to get weird. I don't want to lose her as a friend, because she's so amazing and so sweet... She's the first person who feels like home since I moved to France, two years ago.

I'm sorry if I seem childish, but I'm extremely shy when it comes to love stuff, be it with girls or boys. So I'd like your advice because I don't know how to interpret her actions and I think an outsider's view could be more objective than mine.

Thanks anyway.

 

Hmmm, I'm not sure. We usually do stuff together while being sober. Like we'll meet for a café, or she'll come over to my place and we'll talk for hours, and nothing unusual ever happens - I'm actually so afraid she'll realize I have a crush on her that I make a point in staying really physically away from her when we're alone together. But when we drink, it's different - that's why I'm really unsure whether it means anything or not...

And yes, resu, about her boyfriend, I'll really try to find that out. I guess I'm afraid to know, but it's true I can't keep fooling myself.

Thanks, guys!