It's fair to assume anyone in a relationship will have an understanding with their partner, but can it ever be fair to demand that your partner raise an unrelated child? Maybe this question is best posed to a homosexual. Would you (anatomy187 or other) be capable of unconditionally loving and parenting a child that is not your own?
Your partner can make his or her own decision if they are comfortable raising a child that isn't related to them or not. I'm willing to bet that in nearly every single case of a homosexual couple wanting kids, both partners agree. I doubt there are many cases of one of the partners 'demanding' that they use his sperm (or her eggs if they are lesbians) and that they other partner is just going to have to deal with it? If one partner doesn't like the idea they don't have to stick around do they?
And yes, there are PLENTY of examples of parents unconditionally loving children that aren't their own. Ever here of step-children and adopted children? Wanting to raise a child with someone you love despite the fact that you can't actually have the child with them has nothing to do with an inferiority complex, it has nothing to do with ...most people want to leave a legacy of their own by raising a child, and even though raising one that isn't your own isn't always the norm it isn't all that uncommon either. This debate is even less of a debate since it is about homosexuals who are much more used to going against the norm than most straight people in the first place.
The point is that anyone is 'intolerably inconsiderate' if they force or demand their partner raise or have a child with them according to some guidelines that the other partner doesn't agree with but I doubt this happens very often in cases of homosexuals or even people in general.