Personally I would disagree with, or at least be extremely wary of the morality of abortion regardless of who wanted the child and who didn't.
But if abortion must be legal, then I would say that it should only be legal if both biological parents agree to it. I don't believe that any parent should be forced to lose their child, even if it is unborn. Currently, the law agrees with me, but only in the case of women, which I find very unjust. I also find it unjust that women currently have the right to "opt out" of parenthood entirely by refusing to carry the child, when men do not have such a right (i.e. women may still force them to shoulder responsibility for that child, in terms of financial upkeep). It should be both, or neither. Not one, or the other.