Orgasm-what's wrong with me!

So first off, I've NEVER had a problem orgasming esp when my SO is going down on me. Lol. Last night it didn't happen and I mean like a whole hour long still nothing then we had sex...still nothing!...I am so confused and I felt so bad he was trying everythingggg! I don't know what happened..anyone have this happen to them? I was ovulating too which normally I'm horny and it's much easier to cum....just confused lol :/