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Sorry but I believe in this case it isn't as simple as that. They didn't even solve any misunderstanding with the sex scene, and I believe instead of that, the author intended to show how Uruji is greedy and ugly when it comes to Lamudan's love. It wasn't a scene clearing misunderstandings, it was a scene of Uruji acting rashly, and Lamudan realizing Uruji was that kind of man and how different Uruji was when he acted out of affection for Lamudan (as Lamudan said, attentive during, but not exclusive to, sex). I personally think that was an implication to how Uruji has treasured Lamudan previously.
Yaoi logic- we don't need communication, we just need sex to clear up the misunderstanding