Replying...
Intro. Your boyfriend has a best friend called "Megan" she likes him and he doesn't see him, he's starting to not care about you anymore and pay more attention to her, he stops going out with you to go out with her, she keeps hitting on him, and when you try to talk to him about it he yells at you and gets super stressed and keeps saying "she and just a friend nothing much!, you are very jealous and exaggerated" he always goes to her house and goes out with her, one day you went to call him out and see Megan sitting on his lap in your own room you get paralyzed not knowing what to do, and she quickly leaves his place

Jeongin her boyfriend

@Wonhee