Do I have to claim the money my boyfriend gives me for "rent", now that we're living together?

My boyfriend and I each own our own homes.  Now that we're ready to move in together, he's found some tenants and is renting his house and is moving in with me.  He will pay half of my $1600 mortgage, or $800.  Since he has to claim his tenants' rent as rental income, he wants to offset that by claiming the $800 "rent" he's paying me.  This means I will have to claim the $800 as my rental income.  But is this fair?  I understand I would have to do this if I was renting a room to someone, but I'm not renting to him, we are co-habitating and share a bed/bedroom.  I just want to do what's right and what's fair, we're not sure how the IRS views this situation?