I was single for a long time and I used to get this c* all the time. There's no massive amount of malice involved in it , just the belief of some couples that only their universe exists and everyone else exists only to serve it.
I agree with all the posters that have advised you to prioritise yourself.
No need to lose your friend if you don't want to. Just tell her kindly that being used as a third wheel is upsetting you and ruining your enjoyment of her friendship.
Could she stop please and could the couple sort out their own issues/problems between themselves.
What's one health habit you've started that's actually made a difference?

