Do you have an Ask Emily section? I have an interesting personal query... Guy I'm seeing wants me to get on the pill. We haven't established that we are 'official' but is this the modern way of saying "you're my girlfriend!"?
I think it's actually the modern way to say "I want to have sex with you without using a condom." (The old-fashioned way is just sticking it in.)
Asking someone you are sleeping with to get tested and/or go on birth control (and I hope it's both you're planning on doing) definitely does indicates an intent to continue sleeping with someone into the forseeable future. That, to some people, is the definition of a girlfriend.
But I get the sense that what you're really asking is whether or not him asking you to get on the pill means he wants to be exclusive. And about that, I would say, nothing but your partner telling you he wants to be exclusive means he wants to be exclusive.
Many people in this world are loving creatures who are looking for a soulmate to complete them. The rest of us are dirty, horny dogs who will continue sleeping with other people for as long as we can get away with doing it.
Because monogamy sucks. I mean, it has its benefits, but it's not like taking a trip to the ice cream shop. Actually, it is like taking a trip to the ice cream shop, only you're forced to stare at all the delicious flavors through the glass but you're only ever allowed to eat the same old stuff you have at home. (To be fair, it's your favorite flavor.)
Anyway, monogamy is deprivation and as such, a lot of us like to streeeeetch that magical time after you have started dating someone but before you've had the exclusivity talk for as long as possible. If he hasn't explicitly told you he's not sleeping with anyone else, it is possible he is enjoying the fuzzy gray area of early non-commited love. And you have to either assume this to be true or ask him, or else risk contracting something oozy and drippy.
That said, men are not so good at having those kinds of talks. I had a boyfriend break up with me because I was sleeping with other people instead of just asking me to stop sleeping with other people. So it's possible this is his way of asking you to wear his Nuvaring. I just wouldn't assume that's the truth until you've had a long, lame, uncomfortable conversation about it. Enjoy!