Principally because:
1. Interest rate differential between US and EUR keeps increasing, and is likely to increase more.
2. Intermediate downtrend since EUR 1.30 or so with really strong support in the 1.19 range just taken out today.
3. Can't be a dollar bear all your life!
4. EUR/JPY Cross keeps bumping up against 140 and USD/JPY has moved like a moonshot in the last few days after a protracted range.
Don't worry - long term fundamentals haven't changed. Just look at it as an opportunity to square up, take profit, and buy back in cheaper.