Spoiler one of MC's skills is called "Support Aid" or "Aid Recovery", its a passive skill that can also be activated. one of its effects is to heal your party member's vitality. In excess of this, your body will naturally feel good. Hence why the girls woke up in the middle of the night. The LN Version, if you haven't read it, just had the girls unbutton his shirt a bit, tried to kiss his face, and then stradle his arm. And just stare at him while he sleeps. Like Girls eying a delicious uneat-able pudding. *cough*