If GF feels the need to bring it up on her own, you can't stop her. I don't think it will help, W will dump her too if she feels pressure from her. If GF airs her concern and then drops it, it might not hurt things... too much. Getting others to pull for you never seems to end well.

Certainly don't put your hopes in this basket CB.

M: A really long time.
Crisis: 5 years.
She's still worth it.

Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl