You're right. It feels forced bcus it is. In the novel, I think there were only 1-2 smut scenes and they're short and in the side stories.
As for the prophetic dream, it happened in the novel too but I can't recall if they had sex. Even if they did, it's only implied and not so jarring like in this webtoon. Thus, I highly recommend the novel!!
I feel like it was an artistic decision to adapt it from the novel this way to differentiate this from a bromance, which adds to the anticipation of seeing what other ways they might've adapted it in future chapters. Also, a lot of readers out there are in it for the smut.. even if it was forced, there's a market for it lol
I had to scoop my jaw off the floor when I realized what they'd done compared to the novel. That first scene was NOT expected in the slightest, but now all their interactions have that bit of sub-context that makes it that much more interesting and comedic imo.

The sex scenes feel very forced, with the watch, and it feels like there could be better build up. Sometimes i even forget its a BL until I see a dick in absence of context and chemistry and I and thrusted back into realtiy.
if they either introduced the concept of them having sex earlier (like the dude confesses, or there was already sexual chemistry), because otherwise it just feels like a fan that found his long lost idol and then he had a prophetic dream where he will have sex with him, and then tells the idol **to put on the watch** so he also gets the same dream, and then we're back on the A plot [the BL really does feel like the B plot].
I just want to see them beat this dungeon, I can not give two fucks about the sex anymore.