I think I was more shocked then anything learning about this second relationship because I do know my husband's OW is very strong, successful, educated, and accomplished. I originally imagined her falling into the whole relationship accidentially, even having my "unhappy husband" pursue and charm her into the whole thing (which would be like Spock turning into Captain Kirk for awhile!!!). And then her realizing what a huge mistake she made, feeling really sorry, and guilty about it, and working towards a more substantial life.
There is no arriving, ever. It is all a continual becoming.