IMO the shine will wear off such an ARRANGEMENT (living with OW, teenager and mom). It may or may not take the shine off the affair. I am of the school that most affairs do last much longer than anybody thinks.
Affairs also last much longer (again, IMO and experience) when both participants of the affair can be cozy. My H has an empty house to live in and the OW has her own place and lives alone. TWO empty houses (no kids or other family members) bode well for an affair. An affair, a mom and a kid... not so much.
Your H might decide the situation is not worth the affair. Or, the affair might continue depending on the depth of it and a new living arrangement will blossom.
