Not dating exclusive...Now What ?

I have been dating someone for 3 weeks, and we slept together for the first time last week. We met on a personals website so we were both obviously looking to meet someone. Well, before I go any further and become too emotionally attached, I would like to know if he is still going to be out there looking. I don't want to come across as pushy and I am certainly not trying to get him to marry me, but I do not want to be sleeping with him while he is searching and/or dating others. He says he is "still looking" so should I stop the ? How do I tell him this ? Yes I know I put the cart before the horse, but it is what it is now and Im not sure how to proceed. believe it or not, we are in our 40's. He knew up front I wanted a monogamous relationship, but got the , and now says he's looking.....