I'm sorry Doodler, I didn't see your question earlier.
Jlh,
No problem!
Ultimately, I guess it doesn't really matter too much if he's actively in an affair, or if it's just MLC. The point I wanted to make is that any time there's a third party in a marriage, then the marriage relationship is disrupted and a lot of weirdness on the part of the cheating spouse seems to arise. But, I certainly don't know how to discern between MLC and just plain-old affair behavior.
Given that he's changing his phone number, it sounds like something is amiss so he's probably currently having an affair of some sort.
