Lois, How you approach the situation depends on what you and Larry have agreed upon. Have you verbally committed to date only each other? Did both of you promise to take your profiles down?
If you haven't discussed these issues, it's reasonable to expect that he may still be interested in dating others. Your best bet is to ignore his online activity.
You should also ask yourself if you want to be in a relationship in which you have a one-sided commitment. If that is the case, you don't need to break up. Instead, choose to date others unless he wants to become exclusive.
If you have decided to date exclusively, but not agreed on how to handle your online dating activity, it's possible that he's "just seeing who is online." It's not unusual for a man go online to view women's profiles without intending to meet in person.
It's usually best to allow him to stop cruising online dating sites without pressure from you. One of my former clients wanted me to see what a great guy she was dating. She asked me to take a look at her boyfriend's profile after they had been dating for a few months. I discovered that he had been active within 24 hours. I didn't mention it to her because she was happy, he was treating her well and I didn't want to cause unnecessary anxiety. My strategy paid off as they are now married.
If you have agreed that you are exclusive and that neither of you will use online dating sites, you have the right to initiate a discussion about his activity. But, please use caution. Just the fact that you're aware that he's active on the dating site may cause him to accuse you of spying on him or to wonder if you are using the site to meet other men. It's easy for this conversation to end badly.
So, if you must bring it up, rather than put him on the defensive, wait until you have calmed down. Then, mention how you discovered his online dating activity, and listen to what he has to say. Maybe he was checking out a profile for a friend. Perhaps you misunderstood each other.
In general, monitoring any of your beau's behavior can lead to unnecessary drama. If he's treating you well and lets you know that he's interested in exploring the possibility of a future together within the first couple of months, it's usually best to show him that you trust him by allowing him to choose when he wants to stop online dating.