This was supposed to be a comment on kettledrum's post, but it got a little long:

Condoms and gloves made of latex are used for the purpose of protecting oneself against humans, and more specifically their waste. They also provide a barrier to real interaction by 2 people: while touching someone with latex gloves feels real, it's not skin-to-skin contact.

There seems to be a disconnect between the two people involved in an interaction where latex is involved because both sides feel that they're making a human connection when technically that's not the case. This emphasizes the disconnect in human relationships that I think is evident in both Underworld and GR. In both books characters go about searching for love (both romantic and platonic) in ways that they seem to think will ultimately bring them what they want, but that end up just leaving them feeling isolated though they are surrounded by people.

In both books there is an incredibly large amount of cheating partners and casual sex, and it always seems like the people are searching for a connection in their sexual encounters that they don't ever quite get, like how Nick says (page 344)

"No last names, no echoing second thoughts. This is the pact of casual sex. But I told her my last name and it wasn't casual, was it? That's the odd dominant of the piece, that I wanted to reach her, still her breathing, to make her breathless, yes."----is it really Donna who he feels this way about, or is it the act of committing this moral crime that makes him feel like he's actually alive, or connecting with people?

Nick is the one who said that he was like a one man country, and always had trouble connecting with people. It seems to me that he's substituting casual sex for a connection with a loved one, especially since when his wife starts crying he can't even ask her what it's about and is even relieved to know it's not something she does often as he wouldn't know--this is someone he has lived with for a very long time, I find it a little strange that he wouldn't know if she randomly breaks down crying, or at least be able (or maybe willing?) to be sympathetic and ask her what is making her cry.