To Mark,
You and I've been working on the project by ourselves and comparing notes at lunch. I don't have anything I need to do so I invited you to work on the project at my house. I was super happy when you accepted and it felt like no time had passed at all until you had to go back to your home.
My mom invited you to stay for dinner but you couldn't 'cause you said your mom would get worried.
I did feel sad when you had to go but I knew that we'd see each other tomorrow so I wasn't too upset. I don't know why but I'm thinking about you more and more.
It's probably nothing though.