It is a crappy ending.I mean it's still a pretty crappy ending to the whole Ryn quest
Like let's for a moment try to perceive the authors point of view.
The ending where you can split her with Elthara, a moment where you're meant to consummate your love is split with a third if you don't want to bottom. Given the propensity for sluts, group-sex, gangbangs, and threesomes, this would be the "compromise" option.
And honestly it wouldn't be a bad one if other options existed to keep your tender moment where you confirm your love limited to the two of you without forcing the PC to catch or involving another. Some third option based on her buttslut perk progress, sex toys, mutual masturbation, etc etc. Instead there's nothing.
Without that nothing, you can make the (probably correct) assumption that the romantic love Etheryn has for the PC is equal to the love she shares with Arona (assuming you read those threesomes) and (probably) Elthara.
No choice. Which is par for the course.
All rather moot.
When was the last time Etheryn even got a content update? Technically Evelyn had the scenes where she fucks her updated for the dragon version. Beyond that? Let's check, actually
It's been awhile.
Companions were such a mistake.