I often caution H's who have a WW, about her coming on to him. A WW is so manipulative. If she has not withdrawn all contact with the OM (even looking at his picture on FB), then be suspicious of what you mistakenly see as "reaching out". Many a man has been pulled into the WW's sexual inticement, only to be dropped like a hot potatoe the next day. We have even seen WW's who suspected (or knew) they were pregnant by OM, sleep with their H at least once, so she could convince him it was his baby........if OM ditched her.
It is her way of gauging your attachment to her. As weird as it is, she wants to keep control over your attachment, b/c it's part of that manipulative/controlling symptom of a WW.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!