At this point, I'd just offer to massage her chest or something so she'd get distracted from her withdrawals (yeah no I don't know how bad the withdrawal effects are), don't encourage smoking if they're willing to quit.
I'd actually say it's going the opposite, the sexual acts from the beginning were merely done for experience, just because it's his job and it's their job. The time goes by and the sexual acts they do are more consensual more about about their budding affections. It's not forced, although it's...
Now ain't that convenient, just two slots open for our new hires here. Gonna accuse the writer for being blatant with this but then I remember that some god out there is playing cupid for these two in the first place so whatever plot contrivance that's happening is deliberate.