Boyfriend Won't Let Me Buy Presents

M
Okay so my boyfriend tells me when he wants something. I tell him I'm gonna buy it for him. But then he asks someone else to buy it before I get a chance to give him anything. :/ 
I've never actually gotten to buy him anything and we've been together for 3 years! He always teases me over it too. "You never buy me anything, I always buy you gifts. Do you love me?" I'm so tired of it! What am I supposed to do?