Welcome to Fluther.
We’re your friends now. Finish her!
No, of course I’m kidding. But… that does seem to be a sort of manipulation that she’s pulling on you. It’s either “commit to me” or “give me more attention” or “drop those others” or “I’m needy and special (and therefore need more of whatever you’ve got for me)”.
If you want to maintain the friendship, she’s basically telling you that it’s going to take a lot more of something from you… or it’s a test of whether you will leave someone else to make her more of a priority. (It’s not so different, really, from an abusive husband who seeks to curtail his wife’s circle of friends and acquaintances and control more of her time and attention.)
So, while I have nothing in my life to have ever compared this to – so I have no adequate frame of reference on this – my inclination would be to express sorrow that the relationship will be “put to pasture” (not “put down”, let’s not be extreme), but since it’s her choice to pull away, then let her go gracefully, and keep the door open to a return.