Does she really love me?

She is an adult Border Collie who lives in the music school I attend. While she is a very friendly and warm dog, she is too sweet with me. She always sits close to me, comes for pets and likes nudging her nose into my hand. I love her too. She does that for free and doesn't expect anything coz I don't even have treats. She has her owners but likes my presence too. Why does she like me?