Hotcarls says it best.
F her. Move along and think nothing of it. Youll find that the older you get, the shadier some woman (and men for the ladies) get as well. If youre the BETTER of the two people youll break contact and just man up and move along. Put the feeling to the side and be the adult about things and ignore her. I think weve all had those types of relationships for sure. Just dont do anything stupid like show up at her work and cause a scene, or drop by thinking he'll be there. The last thing you want to do is put him OR her in the position of having to defend themselves.