Kyle isn't mentally stable at that moment and I don't think Ilyan is either. Kyle is most likely too wrapped up in his own mess to really notice what's actually happening. Also, Ilyan will probably say that Kyle doesn't love him or that he was right if he does stop. This is a part of the story's development, and they're not trying to make this scene look like a good scene because of that. Usually, Kyle is really careful with how Ilyan feels during sex since he always says that it hurts but doesn't actually mean it. This shows us that relationships aren't perfect and that good characters sometimes have temporary bad behavior. What he is doing is wrong, and he should stop.
Dude stop. Yes your partner did ask for it however, I think that was a reaction of him not wanting you to leave. Adding on to that he's asking you to stop, he's obviously not feeling well. Plus you mentioned multiple times that he has a fever yet you show no sign of stopping.
Even if you are that horny you can let him go to the bathroom (to puke probably) and you can relieve yourself anywhere in the room.
Please let him rest and comfort him using words or physical affection that is not sex