Boys are really bad on anniversaries or dates in general. They just are. Keep it in your maind - they are like number disabled.
I had most loving father - he tried really hard to make our fiestas great in childhood and later he always was just the best father. He had two daughters, me and my sister, and guess - he was not able to remember our birthdates, he was always mixing them up. Hopeless! We were joking in family about him, teasing, but he was hopeles in this field.
So judge your boyfriend for other things and next time use some diplomacy like - have you planned anything for our anniversary - it is next week?
Just remain it him in the nice way and see what will happen!