You knocked me off my feet

I am falling.
He doesn’t know.
He doesn’t care.
He’s just not into me.
We had sex and it blew my mind. I have no idea how it was for him. We slept together. Like, we took a nap in the same bed, after sex. I literally slept in his arms and it was beautiful.
Now, suddenly, I lost interest in meeting other guys I was in talks with. I only think about him all day and I am scared that I may have developed an obsession for him. I need to keep it cool. I am 45 years old after all, so I should know better.