
Finally! I caught up! I'm one of those people who started off watching Natsume Yuujinchou when it first aired, and have kept up to date with the anime. So I haven't read from the very beginning, but from around chapter 60(?)

I watched the anime then immediately read the manga from the start. It's mostly true but not completely. Sasada isn't in the manga after a certain point (anime kept her) and while I haven't watched the previous seasons for some time (before the new ones), I remember that some scenes of the manga are different to the anime. I personally like the manga more than the anime. The manga is a bit funnier. The anime is pretty accurate though. If you ever want to re-read the manga, I recommend from the beginning.

Answer...
It doesn't matter. If the mangaka wanted us to focus on that, then there would have been panels of them discussing it, or even outright just showing us. But so far it's ambiguous. So I'm guessing we're not supposed to focus on their bedroom antics.
BUT since people in the comments section were discussing it, I'd like to posit this alternate theory: Maybe they're SWITCH
Like, WHY doesn't anyone ever think that they could be switch?

He's a very difficult person to like. Straightforward, okay. Ultimately realizes things he does wrong, tries to rectify it, okay.
Lack of communication, difficult.
Strange sort of selfishness, difficult.
Living with a woman for a year?! Unacceptable!
The trouble with this manga is that we see it almost one sidedly from Yanagi's viewpoint. Therefore the difficult to understand Masaru san becomes dislikable to readers. I wish we could have heard his side, gotten his thoughts.
What makes a straight man suddenly pick up and move to another city to live and try to date a gay guy who wasn't into him?
It's highly unusual.
The reason their relationship lasted so long, IMO, is because Akira just wanted to be loved, and he found a sort of comfort being with Masaru and eventually fell in love with him too. But mainly, he's extremely patient, and understanding, and forgiving.
In short these two strange people make a good match because they compromise for each other- although I personally feel Akira compromises A LOT. But if it works for them, who are we to judge? As long as they end up happy.
Sometimes love isn't great sex, passion and grand gestures and major confessions. It's awkward, quiet, slow and compromising. It doesn't come off as a "great love story", but that depends on who you ask. Just because it isn't ENTERTAINING doesn't mean it's a bad story either

I'm sobbing. This last chapter... I didn't think the mangaka would go in this direction. It's such a cruel situation. Everything's ruined.
Their first time should have been beautiful, passionate and loving.
And Daiki ruined it
I truly thought that Sawato would have caught on before anything happened. But it's ruined.
Just thinking about how I would have felt in Sawato's place... Makes my heart hurt. It's too much. I get why he responds to Daiki the way he does now. But I'll also believe that Daiki will somehow return to the way he was. It won't be the exact same, but he'll find a way to win Sawato's heart again someday ┗( T﹏T )┛
After reading the comments section I expected something more sinister or whatever, esp after someone mentioned Caste Heaven.
But this seems pretty tame so far.
It's not the entire dorm that's involved, just Chiaki's batch mates/ floor mate's. So... I'm not running for the hills just yet. I want to see how it all plays out.
Doesn't look like it'll have fluff ( not anytime soon anyway), so if you're not into casual sex or threesomes, look away kids