What is the problem then?
I promised her to be there whenever she needs me.
"Rather simple", I hear you say. "Break the promise, if you can't stand it anymore" I hear you say. "She's got her boyfriend to take care of her now" I hear you say.
Why promise something in the first place then? Why not just say "as long as there's nobody else, I'll deal with you"?
Because that is just not how you treat friends, right?!

A friend of mine is of the opinion, that such a promise is like a treaty; and since she has someone else, who is well capable of taking care of her, since now I could maybe do better with a bit more distance, the treaty needs a work-over. So the problem now is: are both of us rational people who can not only understand, but also accept this way of thinking and actually live it?
I don't think so; and that's the problem.
Or is it?