Im 39, there is a guy 25 he has a crush on me, he only wants with me and i told him, NO.?

I told him i rather buy a vibrator cause im looking for a serious relationship and I only want friendship with him . I like him a lot too. We only speak once a week, cause he is too busy at work and college, and workout and so on...anyway. What can I tell him so he understand that Im not giving him ??