It's just Larian being Larian, as soon as they showed the cutscene of him chilling without a shirt on, I just skipped straight to the "i want to sleep" line, and cut it very short. They just have to make things weird.
The Mind Flayer who retained the identity of a human is also a human, and deserves the right to love. He is very lonely and can maintain his Dream Guardian form during sex.
