Why does this bother me?

My fiancé and I are expecting our first baby together. He has been talking to the baby since the moment the test came back positive. He talks to the baby every morning and every night. He told me the other day that he never once talked to his daughter while his ex-wife was pregnant. He loves his daughter so much, it's so easy to see when they are together or you can hear it in his voice when he talks about her, but he didn't want a baby at the time. His ex stopped taking her birth control without telling him.

I'm not sure why, but I feel sad or hurt or upset... or I don't know... about the fact that he never talked to his daughter. Any insight on how to get passed this?