Sometimes I really wonder how some interpret certain tags.
First of all, of course it's and adult +18 game. You do realize that even if there was no sex, just some titties on screen and nothing else, for the whole game, that HAS to be tagged as +18. You do realize that? Unless I want to get banned for people under that age playing it.
Now with that false claim out of the way... This game is intentionally slow. It's even pointed out on start of it. If you wish for a quick meet and fuck, this isn't the VN for you. And if you take a smaaaall peak above, you can see the tags. Dating sim, romance, slice of life, meaningful choices. I think all of that is absolutely correct, isn't it?
Also, an adult game doesn't have to have a sex scene in first episode, hell, some have actual sex way, way later into the game. So far, there is one boobjob scene ingame, and some more scenes will be coming in Ep4. And if you only care about Sex scenes, well... Plenty of such games out there that start as soon as you load the game ^^
Glad to hear you like the story though.