Daddy Blues

Ok so our daughter is 8.5 weeks old...and my husband and I love her to pieces! So anyways, tonight was my first night leaving him alone with her for a few hours as I had an event at my church and he really wanted to spend some time with her. I was gone for 4 hours, and left him with 2 more than full bottles in the fridge. I called him on my way home and he sounded just totally drained. I asked him what was wrong and he said that she hasn't stopped crying for the past 2 hours and he couldn't figure out what was wrong. He's a great guy but I guess not the most patient....he said he had to end up putting her in her crib to cry because he couldn't take her screaming in his ear anymore. Him and I talked when I got home and he was just expressing to me that he gets frustrated with himself because he can't figure out what she wants. I told him that he's a good daddy, but he said he doesn't feel like it. Then I said "you tried your best" and he said "what if my best just isn't good enough?". I'm trying to make him see that he indeed is a good daddy but I don't know how. I know he loves our daughter with all of his heart but he's beating himself up over the fact that she is content with me but when I leave she's good for awhile but then won't stop crying. Any advice I can give him or something I can tell him to boost his confidence?