I didn't tell my boyfriend that I'm going to the cinema whit my families and cousins because we had an argument before and I'm verry verry verry pist off with him then I just turn off my mobile phone till I went to the cinema. At the cinema, I saw him and his friends (btw he did the same thing,he didn't tell me that he was going to watch movie after work)(he works near by the cinema fyi) sooo,most of my cousins that I hangout with is boys. When he saw me standing near my coousins,he thought that I went out with friends(boys) and didn't tell him about that. He thinks that I have something like a relationship with my cousins which he doesn't know that they are my cousins. He thinks that I'm a player, he thinks that I don't really love him or care for him but actually, I DOO. REALLYY. SERIOUSLYY. But now, he's mad at me and don't want to believe me about all this. But I've told him the truth. PLEASE HELP ME WITH THIS :'( . What should I do?

If he is still mad after you have explained then he is a jerk. Loving a jerk is no fun, and who cares what a jerk thinks? Leave him alone until he apologizes for being a jerk, and a dumb one at that.

If he doesn't trust you enough to believe you then why are you with him? Without trust you don't have a relationship.

You told him the truth. If he chooses not to believe you, find someone that will.

There your cousins, when you explained it he should have understood. If he doesn't and is still mad I don't think he is worth you time, he just being a jerk and finding any excuse to be mad at you for.