I'm missing something...

So my boyfriend and I have been together for a little while now, but we've had a rocky road to getting in a semi sound relationship. But we're in a good place and have been for awhile now. We've had sex a couple of times, but this was like 6 months ago. Since then it seems that he doesn't want to or something. We can be fooling around and he will act like he wants to, but then just won't go that far. He's a bit older than me, so I'm sometimes intimidated by the differences in experience level so I'm probably more reserved and wait for him to really initiate things. It's gotten to the point where I'm starting to get confused as to why he doesn't want things to go in that direction for us.

Anyone ever experience this in their relationship? What do I do?

Any idea behind the reasoning?