Lan Wangji and Lan Xichen
It was true that he enjoyed Jiang Wanyin's company and that they were growing close. However, they had not hit the stage of waking up in the same bed together. Nor had they really talked about how they felt toward one another. So, it was more than a little awkward to end up on a cruise ship and find one's self... in bed with someone they liked.
"The room we woke in only had one bed, Wangji."
It would give his baby brother a bit more context on why something would be more awkward.