The factors and behaviors listed in the post presented by Pat are totally accurate...
I was thirty-one, unhappily married with a small child, and enrolled in a painting class while living in VA. After the first class, I was smitten by the painting teacher, 20 years older, a Svengali seducer type, if there ever was one. I worked very hard to be his star pupil, and spent every waking minute anticipating my next class. I took his class for several semesters, just to be in his presence, and gradually began confiding personal things to him. He told me, at one point, he would "take care" of me, and invited me to his apt. I left my daughter at preschool, and went there, thinking we would talk about "us," but all he was interested in was having sex, which I couldn't do! After that meeting, he stopped all communication with me, though he had been calling my house at night after my husband and I went to bed.
It literally took me 10 years to recover from this, during which time I desperately sought counseling. One counselor told me an emotional affair can be a devastating and require as much recovery effort as a physical one!
Patty