If you feel knowing the gender would make your DH disconnect from you and the pg, then I wouldn't find out. I've been through a pg where my DH had absolutely zero interest in the pregnancy right up until the last few weeks and it hurts like you would not believe - our first pg was a surprise just after we got married and DH was not prepared for that at all as he wanted to wait a while to have a baby and when he found out I was pg he completely withdrew from me. Experiencing all the happiness and special moments that being pg brings was really hard because I had no one to share in that with me. And you really notice the lack of support as well and I think you being supported during the pg is more important at this point in time. But I think you really need to talk to him about the way he feels and find out exactly what issues he has so you can work on them because it may not change after you have the baby either.