I'm not sure that there's any difference -- an affair is an affair -- but the timeline you describe is EXTREMELY common. I think it's called "normalization." "Normalization" refers to the process a wayward spouse will go thru in order to get their circle of family and friends to accept their affair partner. It is VERY important to them that everyone do so, and it's typically part of their fantasy that "everyone will be okay," and "will all get along."
Rarely does a wayward spouse envision any push-back, or at least they vastly underestimate it.
It's also VERY much typical "script" for a cheating spouse to deny the existence of an affair partner, until some time later, AFTER the marriage is either divorced or formally separated. Then, "all of a sudden," the wayward spouse will announce to their family that "I've just met someone."
That's one of the risks of just leaving these things alone: the illicit relationship just deepens, and the wayward spouse is just blocked, emotionally, from seeing any of your positive changes.
