Asking out--but there's a catch.

I went out with a group of friends last night, and I met a girl that I'm probably going to ask out. Catch is, she's clearly friends with another guy that was there, but I couldn't tell if they had a relationship or if they were just friends. When asking out someone in a situation like this, what's the best way to go at it? Oh and let me be clear that if I find out that they are indeed in a relationship, I'll call it off right away.

Same as if she didn't have a male friend. You strike up a conversation with her, nurture some chemistry, and if it is there, kiss her and get her number. If she is unavailable, you will find out soon enough. It's not your responsibility to figure out what her attachment status is before approaching her; it is hers to tell you that she's not available to you romantically.

OK, good to know.