Yep, that was what crossed my mind as well. The phases of affection and attachment you two mentioned are just such a common thing to me, that I didn't thought of them as problematic. I know that this will happen. What I didn't understood was the emphasis he laid on the biological part of it. Maybe this problem will solve itself with the experiences we make later on. Because, when we talked about child-rearing and responsibilities and attachment to the children and hopes and expectations, he forgot about the whole 'my flesh and blood' thing and was on the same page as Sward or I. Maybe it is just a switch in his head that will flip as soon as he is able to experience the situation, we all know that we are just speculating right now.
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.