I got a lot of good feedback, mostly along the lines of "say that life is hectic right now and you don't have much free time to spend socially."
I've tried this approach, to no avail. The girl ain't getting it. She stops by my desk and more adamantly proclaims "we should go out! let's make plans to go out!"
I am still at a loss as to how to respond to these invitations, and I want a nice catch-all phrase that says "stop inviting me to do crap. I don't wanna." But of course, I don't want to come across as bitchy. Can this be done and, if so, have any suggestions as to how to phrase it so I can end these invites once and for all?