My cousin (20) and I (17) used to cuddle and flirt every time we meet. We do that when our parents are not around. We meet once in a year. We haven't expressed our love for each other. Is he in love with me? 


Most likely not. He enjoys the sexual stimulation that comes from cuddling and flirting with you, but this is not love. See:

There is no way you can have love from brief meetings once a year.