The game has many paths, so it's hard to estimate how long you'll enjoy it.
Some players go through it once and call it a day. Others try a few different paths, and some aim to unlock everything.
It also depends on whether you enable or disable certain fetishes like NTR, disabling them will skip related scenes, which means less content overall.
Your best bet is probably to check the Steam reviews to see how long people have played and get a rough estimate from that.
Hope this helps!