Why do I get so tired around my partner but am borderline insomniac by myself?

Anabelle

Is it normal to get tired when you’re with ur partner? Idk what it is but whenever I’m with him I get so sleepy, to the point where I am almost falling asleep but when I’m by myself I’m not tired and can stay up late 🙃 like rn I’m not that tired. Does this happen to anyone else and does anyone know why?