I forget to say "I love you"

I am having trouble justify when is the right time to say the three words. Was there a procedure telling you, you are allowed to say the 3 words after you've spending certain time in dating? Or you can only pop these words only when he said them first? Or you can only say them during the special occasions? The more often you said it, the less meaningful they are? I have so many questions in my mind which I don't know who can answer. Therefore I went with what my heart told me. I said it when I feel like telling him "I love him." I said it when I am in loved and when I adore him. ------------------------- Time after time, I notice that he also said the words; but instead of the 3 words, he uses 4 words now - I love you too. My curiosity struck me, so I had to ask why he did not say the 3 words to me anymore? He said " I am sorry, sometimes I forget. Please remind me if I forget next time......" ..................................