Why would my ex girlfriend add me on facebook ?

[Andrew]

In my experience (which I must admit is not extensive) of ex girlfriends, they tend to want to stay friends after a breakup.

[quietcast732]

Could be 3 possible reasons:
1. She just wants to be friends with you and be able to keep in touch.
2. She wants to be able to keep up with you and see what's going on in your life without having to ask you directly now that you're not with her anymore.
3. It's Facebook. People add just about anyone if the name and picture is familiar. And some people even add complete strangers. Facebook requests aren't really a big deal as they used to be anymore. Honestly, it might not be such a big deal and you probably shouldn't look into it too much.