Re: Girl needs guy's opinion!
When you say "dating" I'm going to assume you mean that you are NOT in an exclusive relationship. Because of that then the most likely reason for this behavior is that he is exploring another dating option. Of course he wouldn't tell you that since he wouldn't want to upset you or lose you. And it wouldn't be fair if you held that against him. It's perfectly healthy to date multiple people if that is what you are into.
If you are getting serious about him then maybe it's time to discuss a relationship. Granted it is still fairly early and there's still much to learn about each other, but it could help bring you two closer and maybe have an actual argument for the first time. Lol
If you are not trying to get serious yet then just accept that you are not exclusive to each other and are free to explore other options.
As for what you should do at this time...just keep being yourself. If you start questioning him and acting insecure I can guarantee you will push him away. You're better off behaving as if you have no competition with other women because you understand your value and no other woman comes close. He will see that while the other girl gets insecure and he will come back to you. Hope this helps and good luck.
"All things are subject to interpretation. Whichever interpretation prevails at a given time is a function of power and not truth."