hmmm i can give you a few answers. realistically we don't actually know them so who knows but my main assumption is chenle just had so much fun with jaemin right before this show so he wanted to continue with that fun. also from what we know while resting together jaemle cuddled and chenle especially was really clingy with jaemin. i think that's also a part of it! jaemin puts up with chenle's very touchy and cuddly side and even enjoys it and that makes chenle really happy. meanwhile if we look at how jisung and chenle react to skinship with each other, they seem to get quite flustered/blushy/shy around each other in those moments. so i think if chenle shared a bed with jisung, he wouldn't cuddle up with jisung because he'd be too flustered to try and jisung would also get flustered too so... i think assuming they would fight is definitely too extreme haha chenji are very close but awkward hmmm... i would say flustered more than awkward! jaemin indulges chenle's touchy instincts and that makes chenle extra comfortable around jaemin so i think it makes sense that he feels more comfortable rooming with him... it doesn't mean he would have a bad time sharing a bed with jisung though!! they just have different dynamics~