Welcome to Cruise-Chat! I was on a Crystal cruise in February (you can check out my review at CruiseReviews.com) and your question is not an easy one to answer. If you are looking for a late night, singles scene, then Crystal is not for you. However, they do have gentlemen ambassadors as dance hosts and the staff is absolutely wonderful!!! Even the officers, mingle and make sure everyone is having a good time. You will find that there usually a number of single passengers on board (just not the partying type).
Hope this helps and once again - welcome!