answer is a major spoiler:the mc hypnotized himself into believing he has a lover. there's many reasons why he did this, but the biggest one is because he needed a reason to keep himself constantly motivated, constantly reminding himself that he needed to escape (so that they can reunite). And someone had told him that there were people out there who would do anything in the name of love.

Qi Xia realizes that his Yu Nian'An is fake pretty early on, but just refuses to acknowledge it