If you haven't seen Yuyushiki, it's a delightful little healing, slice of life comedy. It follows the 3 members of the Data Processing Club (they just look up interesting things on the net) and their sweet and loving teacher who they can't help but call Mom (hence the nickname: "Mom Sensei"). In fact, it was so good, I think I'm gonna watch it again! :)
This hentai was just on the edge of what I feel comfortable with. But I figure you could easily take it that she's really enjoying this whole thing, even if she finds the sex really intense.