Am i overreacting ?

Me and my SO were having sex and said he had to go to the bathroom so i asked him was he coming back to make me cum amd he said yes . My cousin is here and though i am jealous of their relationship , he always lie to me and spend WAY more time with him than he do me . He went upstairs and never came back so when he finally came back he was putting on socks and i asked was he walking his boyfriend to the store and he said yes so i asked what happened to him making me cum and he said he going to when he comw from the store . When he came from the store he never came back downstairs , he is STILL up there with him with an attitude with me because im upset he keep leading me on and he always make me feel like he doesnt really want me ... am i overreacting ? And if not what should i do about it ?