Responses
It’s implied without explicit words that they were sleeping together in the previous timeline for like 100ish chapters (Yuder’s narration will say things like “he’d seen Kishiar’s body more than anyone expect perhaps his wet nurse” and “he mostly saw Kishiar walking out of his room at night”), and then they do eventually explicitly tell you that they were having sex really regular in their past lives ever since Yuder went into heat for the first time and happened to run into a similarly in heat Kishiar
The next chapter he will ask him to sleep with him.