I hear what your saying on how things can turn at a moments notice. In your situation I don't know if OM was involved or not but in my case there is. Old high school BF, they hadn't seen eachother since they were 18, W is now 46. OM has been married 3 times with 5 kids & lives 3 1/2 hours away. He only contacted my W when he had a marriage or relationship end. This time it was my W turn to contact him saying "can't believe I'm getting divorced for a 2nd time." Turns out he was also ending a relationship so they could cry on each others shoulders this time. This was my 1st marriage her 2nd, 2 S from 1st marriage 1 D from our M. So there are kids involved.
I don't know if they are truly ment to be together or not based on the number of failed M's between them but they sure picked up quick from where they left off 27 years ago, This could be a rebound R or not but I do think its a fairy take romance/ high school romance based on how their acting.
I do know that I wish W would of been alone for a while to think about our M instead of jumping into an R that she told me was "easy & convenient to be in". W has also told me that OM doesn't want us talking about our M, she has to be with him 100% or not at all. W said she respects him to much based on what OM has done to go behind his back.
I along with other people say this is just a rebound R & that she may also be having a MLC. In any case I the H feel like the Plan B person & that 100% of W's effort is being placed on OM. On another note W is also 'testing' me on certain things when we speak, seeing how I react to things that have happened ex. Her almost closing garage door on hood of car. It didn't happen, sensor stopped it but if it had as she said "would I of yelled at her?" Which is what I did in the past yell at small things. I told her "no it would of been an accident, I don't yell about small or large things anymore."