Sex drive issues

My boyfriend has a really high sex drive and so do I. But recently, the last two days mine has lowered since I got on birth control. We still have a lot of sex but I don't always want to have MORE that day which frustrates him.

Such as yesterday, we had sex three times in about 6-8 hours. I was beginning to get sore and losing my 'horniness.' About 30 minutes after round 3 he is up and ready for 4. I'm obviously not into it and I tell him that and he puts a frown on and turns away. The rest of the day he gets frustrated which is understandable but it's so hard to deal with. Like if I don't fuck him one more time regardless of how I feel he's not gonna be in the greatest mood. And I already try so hard, with 3 rounds. Does this makes sense. How can we fix this? How can we make things easier?