but i already did that elsewhere, *quickly thinking something to say* he is aboarable
Well, it is too long if you pick every option yes, but you can skip through if you select the last options so that's nice. From my experience with VNs, i find that interactive sex scenes can be fun the first time but then become obnoxious to go through each time you want to try different interactions of the story, yours at least get the avert eyes option, but Asterion's kiss suffers from having too many subsequent options at once. If you want an example of how much interactivity and variations a sex scene should ideally have, i recommend checking out "Burrows" latest update on Mark's route, to spoil a bit if you don't have the time there's 4 big variants, one being a solo and 3 fantasizing about different characters. I do give big points for animating the scene, that's an extra step few VNs have started doing and is still very uncommon. I do, however, want to point out that i don't know the average reader preferences for these scenes, so my one opinion doesn't account for deciding if scenes should have more or less interactions going forward.
Not wanting to intrude or anything, but I felt the length of the scene was warranted. Put it in the context of Khenbish thinking back on a moment in time, a "missed opportunity", fantasizing about how his first sexual experience could have been, all the different things he wished he could try and all that. I specially like how the scene builds up, starting shy and exploratory slowly gaining confidence and gathering momentum for a satisfying climax.