Jas, Of course every situation is different, but if OW was away for a while and recently came back to the area, you're right, they are probably in the honeymoon phase again. And if she's a serial cheater, I bet you're right in that she'll be moving on once "this" relationship gets boring.
If the course you've decided on is to wait this out, just detach and love your kids. My kids have been my strength.
My counselor told me that in my sitch it was probably a bad thing that OM moved 250 miles away because that removed the opportunity for WW and him to get on each other's nerves. I have seen times when they'd get into it with each other and then he'd be all "I'm sorry, I can make you happy forever, blah, blah, blah". If I'd have been stronger I think if I'd have just ignored the affair it would have ended on it's own, but it's not in my personality to sit by and watch my WW leave to spend the weekend with OM without doing something about it, so I went the exposure route. Did it work? Remains to be seen. It's pretty much ended the affair, but now WW thinks I'm the most controlling cuss around because I wouldn't stand by and let her have an affair with a married man.
Keep your chin up.
Hope4us
Me - 49, W 49 S22 & S18 Dday 9/4/07 W claims NC 4/7/08 8/29/09 - Divorce Busted. Lots to work through, but we're going to make it.