Is love at first sight really possible? Girl fell in love with me.

I came home on vacation (I live like 1000 miles away from my family) and went to a party. I met my sister's friend and within 30 mins we were stuck to each hugging and lovy dovy for the next 4-5 hours. We talked through the whole thing.

For the next two weeks we made love and spent at least 8 hours a day non-stop talking. We agreed to a long distance exclusive relationship.

I'm leaving to go back home tonight and she gave me a physical letter with a written essay basically saying she felt like she met her life long partner and she wants to spend the rest of her life with me but if it doesn't work out then she understands.

I feel the same way with her too but it's overwhelming to the point where I don't know if it's truly reality.