1. Mood: Something about the night makes a woman a bit freer. It is not necessarily the darkness, it is the ambience, quiet, and the overall cover that the night offers. This is why intimate dates, quiet walks, heart-to-heart talks, etc always seem so much more romantic at nights. It is this feeling that makes her want to connect with you at the end the day instead of during the harsh light of day.
2. Relaxing: After a very busy day, most men just want to hit the sack, but not women. Some women might prefer to have a glass of wine, surf the net or watch some TV to unwind before bed, while some will prefer to have some fun with their men. The point is, women prefer to gradually unwind before actually going to bed, and se.x can help with this