There's Something Wrong With Me?

My boyfriend tells me repeatedly that I must be bipolar. I hate to admit that I sometimes have behaviors that do not understand myself. For example, yesterday was quite happy with him and decided to go to the supermarket get dessert, but he entered the supermarket where there isn't a dessert that I like. Just because it i changed my mood, I was aggressive right there with him and although i had the consciousness that i was acting wrong with him, could not prevent this behavior. Back home he tried to calm me doing various things I like but my mood doesn´t changed. Even he was distressed because of the flu and need help and I could not help him to be very upset. This is just one example, but these episodes also happen to other people with whom I have a closer relationship.

I do not know what it is, but I hate feeling this way