if I didn't have the crush, I wouldn't be so upset, no.
I have been assured by both my primary partner won't leave me, and the my partners GF won't let it get that far.
the GF has said she just can't think of me as more than a friend.
and I think you are right, it is more envy than jealousy.
I am new yo poly relationships, as previous GFs of mine were mono. I belive we may have worked out a way to make me feel included that all are comfortable with.