I agree with others, how you cope with your disappointment is all down to what happened to make you feel like that in the first place. Disappointment is not a nice feeling, especially when it is someone you love - so instead of concentrating on whatever happened, think about the reasons why your boyfriend has made you happy in the past. We are all human and all capable of causing others to be disappointed, remember that and any times you may have caused him to feel that way about you. If the reason behind how you feel is huge, such as cheating etc, then that is a different story and really depends on how strong your relationship is and whether you want to make it work or not.