<human>: Like the title says, I've been spending quite a bit of time with this girl over the last couple of months; we've known each other as friends for about a year, the entire period of which she's been in a relationship with another guy.

This fall he moved out of state to attend another graduate program, and since then she's been approaching me (by text or in person) to hang out one-on-one on a fairly regular basis -- something that never happened previously.

I initially wasn't sure what to make of it, but based on certain aspects of our rapport (body language, etc.) it seems like she's at least somewhat interested in me as more than a friend. Also, I've heard from mutual friends that she's more-or-less checked out of the relationship at this point (and she never mentions him when we're spending time together). The mild flirting and getting to know each other has been great, but I'm at the point now where I'm beginning to wonder whether it's worth wasting my time if she doesn't intend to break it off with him. I could definitely see myself dating this girl seriously under other circumstances, for what it's worth.

My question is: how do I move forward here? We'll be taking a four-day trip with some friends in the near future (her boyfriend, as usual, will be absent) and will have lots of opportunities to spend time alone. At what point does it make sense to flat-out let her know I'm interested and ask her how she feels (is it wrong to even do so, knowing she's in a relationship)? Do I just make a move (i.e., go in for the kiss if it feels right)? Or just keep hanging out with her and see what happens? I don't exactly want to be the one to break up a relationship, and I think I'd draw the line at helping someone cheat, but this one seems like it's on its last legs.

Give me the gist of the text in a nutshell
<bot>: Girl in relationship approaches me, we start hanging out and now I'm developing feelings for her, but she's not planning to break up with her boyfriend. What now?