She did it again last night!
Saw her in the midle of last week, asked if she had plans for the weekend, she said no, I said neither did I so she should call me if she wanted to meet up.
Yesterday evening she texted me "You're going out tonight?"
me: "maybe. You?"
she: "don't know"
me: "wanna go for a drink?"
she: "humm... where?"
me: "x-place, y-place, z-place (naming a few bars in our area). Or you make a sugestion"
she: "do you think (another female friend of ours) is down?"
me: "don't know. Text her and find out

"
she (after some 20 min.): "She is with her friends"
me: "O.K. so... you wanna go out or not?"
she: "It's no fun if we're just two. Who else should we call?"
me: "don't know. Still, just the two of us beats staying at home. Even if we just go for a coffee"
she (after almost two hours, although it may have been a delay in the service provider, because the timecode on the txt didn't match): "I don't know if I want to dress up and go out just for a coffee lol"
me: no response
Any toughts on what went wrong here? So far I have three theories:
A) she wanted to party and really didn't want to hang out with just one guy
B) she wanted a chaperone, and flaked because the other girl flaked
C) she was desapointed when I mentioned "just a coffee", but my first option was to go for a drink, and even gave her the chance to pick the program, so that's probably not it.
I have previously hang out with both girls (concert), did some kino with both, concentrating on this one, but didn't close or escalated as much as I should because the other girl was with us. Still, she responded well to my escalation and was closer to me every time we were together after that.
Can someone tell me what went wrong and how can I do it better next time?