Originally Posted by RickX
Just to share my situation which is quite opposite from OP's. I'm male and in a V with a married couple (they have 1 child). My gf and I agreed that if ever our relationship will result in a pregnancy (either unplanned or planned), the child will be recognized as their own. She will not be interested in knowing the paternity. According to her, my metamour agreed to it. I somewhat resent it because I wish to be a father someday, but nothing is permanent. Her mind could still change in the future.
Her husband agreed but what about you? This is a classic case of couple privilege where they made a plan about your relationship without even your input, but you seem to be passively accepting it so...what do I know?
The only things to suggest is 1) Take contraception into your own hands, make sure you use condoms since you want children one day you can't have the snip and 2) Do not rely on her one day changing her mind and 3) Make sure she accepts that when you want a primary relationship for yourself in which you will be able to happily create children and raise them AS THEIR FATHER, which is your right and if she is unwilling to be open to that, say goodbye.