you'd have been forced to have a relationship with douma, since he fell in love with you, so because you're the first person that he loves he's very, VERY jealous, so one day you asked him to go sleep on your sister's house and he let you, but what "he didn't know" is that you're planning on go sleep on your best friend's (boy) house...

You come back from your friend's house

-- Oh, Hi dear, how was it at your sister's house?~ smiling