Flirting with Death

I discovered a way around it, by making him a played character, then moving him into and out of the trait GrimReaper. There was (as of weeks ago, who knows about now) a rather long lag somehow, between going from being de-reapered, to reapered again, for what interactions were possible. So I would de-reaper him and start the serious romantic interactions, then in mid-woohoo, apply the reaper trait again, and he would finish it, in full reaper mode. And for some bizarre reason, for something like a minute afterward, my Sim could still exchange passionate kisses, full-on kisses, and other interactions, with the Reaper even while he was faceless, footless, and deep-voiced, gliding on black smoke. But then after whatever short time period had elapsed, those interactions again became impossible.

But this get-around did let me have Cassandra Goth marry the Reaper, have a gorgeous wedding with full-on faceless kissing, have woohoo with him in Reaper mode long enough that she had offspring who bore an unpredictable mix of either the unmasked weird reaper face that all reapers have (it's eerily beautiful and unsettling like looking at a Manticore) or the dusky complexion, or both. Maybe how the offspring came out depended in part on how soon into the Try for Baby interaction the re-equipping of the reaper trait happened.

I also found out that Reapers, despite all having the same face underneath the hood (is the face just a mask, perhaps, since there's no neck?) have individual personalities and traits, like other Sims.