Umm?? Confused?

Okay so me & my boyfriend have been together for about 8 months now. We've been having sex for 6 months.. We've had some amazing ones, some average. But the last like 4 times have been "off the roof" amazing.. Why is it all of the sudden getting amazing? Will it stay this way or eventually go back to getting average or get better Orr? Why is it suddenly getting better is basically what I'm trying to ask.. Thanks (: