Personally, it's exactly because it's not a sexual series that I never understood the expectation for sex. The desire to see it? Sure. But there seemed to be an expectation for something the series never was or tried to be. If this were "Asumi-chan," then yeah.
It doesn't even have to be Asumi-Chan, in various milder series the main couple has sex, Girlfriends, Kase-San, Bloom Into You, and others. As I said it's fine if it's off camera even, and personally while I don't expect sex I'm glad when it's included in some way because a lot of media tends to be very sexless.
As for people's expectations, I think Citrus at least early on was commonly thought of as this spicy taboo romance that would go places a lot of more fluffy romance wouldn't. That it would be more along the lines of Flowerchild's works maybe. Also perfectly fine if you don't agree with that impression, it's just the impression I got back in the day and some of what I saw people expecting when the original series first started. I sometimes still see social media treating Citrus like the most unholy and taboo of all lesbian romance because of the "incest", which feels like a joke to me but somehow people are serious.