What does he want me to say?!

My boyfriend is very like sentimental and wants me to tell him something that will make him believe that I truly will always love him. Everything I said wasn't what he was looking for. Then he said to pretend he was a 13 year old and tell him something that I would do to make him believe that I truly love him. Some times this kinda stuff just gets so ugh with him cause he repeats himself a billion times no matter what I say. What could he wants as an answer?!