What do Real Estate & Singing have in common?

I can't seem to get into real estate topics like my husband would like me to.  Topics relating to money figures and crunching can be such a bore to me.  Is it any different if I started talking about a topic I'm interested in, but he's not?  I think that a conversation about keys, notation, technic and other aspects of singing might bore him as well.  Married individuals somehow have to find a balance in each others interests, while still letting each other "fly".  I guess I'm just not sure how.  How do two people "fly" together?