Do you think?
...that NRE lasts a lot longer if one party (probably the female) holds out on sex? Z has a secondary that is celibate (so far) and it seems to keep the NRE alive. They have known each other for years but their connection deepened when his marriage ended. It seems that unconsummated their relationship hasn't moved out off the NRE phase. They kiss and cuddle and she massages him which is probably just enough to hold him in the space.
What do think, I'd be very interested.