I'm so confused! Why won't my BF call me?

So, My BF and I have been going out for 3 months. We got in a slight tiff on Friday night when I asked him why he doesn't want to have sex anymore. It was bad timing on my part, however he got really angry and told me I was being an a**hole. I left and he hasn't talked to me since. I know he went to his lake house with his best friend and son for father's day over the weekend. I wished him a Happy Father's Day in a text, but he never answered. I also tried calling him Sunday night with no answer. It's not like he ignored my call either, he just let it ring. He started a new job about 3 weeks ago and has been really stressed and tired and not himself since. I really care about him and want to make it right. What should I do? Should I give him a few days to gather his thoughts, or should I just throw in the towel now. In case it helps, he still has all of the photos of us up on facebook, we both still have the location program we downloaded on our phones and he hasn't deleted me. He works like 13 hour days and is usually exhausted by the time he gets home. He even admitted the night before our fight that he has been really hard on me. Should I just assume he is busy and give him a few days to work through it?