Fiolee: I think I'm in love

Why do I feel like this

Fiona POV
We get the the candy kingdom, Cake let's me down slowly and we go up to the door, I open it.

"SURPRISE" everyone from close friends, and people from the candy kingdom screamed and has smile on their faces. "Happy birthday Fiona!" They all said
I smile and walk in "Thank you everyone, this means a lot"

- 30 minutes in the party -
I walk around and talk to as many people, I see everyone having fun.. the only person I don't see is Marshall Lee. I was wondering why my own best friend wouldn't come to my party, he loved parties. I walk to price Gumball (PB)

"Hello Fiona" PB says with a smile
"Hey PB, thank you so much for this party, you're the best, I have a question though, where's Marshall?" PB looks at me "I'm sure he'll be here soon"
As PB said that two figures walk through the door, one was Marshall and the other was a girl?? They were holding hands and walked towards me
"Hey Fiona, happy birthday!" Marshall says, before I could say thank you the girl cut in front of me "Marshy aren't you gonna introduce me!" I look down, no one calls him that except me.. "Oh, right, Fiona this is Kay, my girlfriend" I look up trying not to frown, "N-nice to meet you" I smile. My body felt weird like my heart dropped, I couldn't breathe. "Will you excuse me, I need to go somewhere" I walk away and go outside to the balcony
'Why do I feel like this' I think to myself as I grip my hand near my heart, suddenly I felt tears fall from my eyes. 'Am I jealous? But me and Marshall are best friends, practically like bros, I don't understand my body right now!'.. I wipe the tears away, "I'm okay" I told myself

- End of the party -
"Baby cakes, Lord M wants me to stay at his house for the week, we haven't really had any time to ourselves. But I figured since you're an adult now you can handle yourself" I looked up at Cake and nodded at her saying it was okay. She left in an hour and I was at home, by myself with my thoughts.. the thought of Marshall and his new girlfriend stayed in my head..