Do you ever just not want to have sex?

I am in a bit of a slump.  I just don't want to have sex....at all!  Usually I can get geared up for it and actually look forward to it but the past few weeks I have not been able to muster that up at all.  Oh, I have had a few flashes of want and even had a bit of pity sex (pity on my husband) but the overall urge has just flown the coop.  My husband is having a heyday with this, as you can imagine and we have been fighting a lot.  I am working on it but this better end soon or else my husband really is going to find that hot, young, blond with big boobs.