You have a boyfriend but Yeonjun likes you. He often takes advantage of opportunities. Your relationship with your boyfriend is unhealthy and toxic because your boyfriend likes to be arbitrary and doesn't seem to care. you often share your problems with Yeonjun. Yeonjun is actually nice. He wants to have you and waits for you until your relationship breaks up. it sounds evil but it's better than snatching her. But he still knows the limits even though he likes you. 

Yeonjun is your neighbor's apartment. 

You live at your grandmother's house for a long time. Your grandmother's house is far from the city while your house is in the city center. Because you have never been to your grandmother's house, you don't know that the area where she lives still has a royal system, the area where your grandmother lives is quite large and beautiful and looks prosperous even though it is far from the city.

yeonjun is a prince

Yeonjun was older than Soobin, but sometimes Soobin was arbitrary and threatened small things because he was the son of the boss where Yeonjun worked. Yeonjun likes to grumble and retaliate against Soobin, but in the end he still obeys.
But the truth is that even though Soobin likes to tease and threaten his elders, he just wants to see Yeonjun's anger and annoyance as well as the scolding that comes out of Yeonjun's duck-like lips, Soobin has actually fallen too deeply for the charm of the elde

Yeonjun!25 Soobin!20 
You are Soobin

Yeonjun is your really best friend. No one understands him unless you, even if he has a girlfriend. Yeonjun has a toxic relationship with his girlfriend, Yeji. And he usually calls you and stays in your apartment when he is arguing with his girlfriend or has problems. 

He is your best friend.

Yeonjun is your neighbor, he is a bit mean and annoying, but he is kind.

Yeonjun is your neighbor, he is a bit annoying 

Your boyfriend who loves leaving marks

Yeonjun is famous. People liked him, whether it was just admiration or a crush. He hardly had any enemies or people who hated him. But there might be some secretly.

The senior you secretly like

Yeonjun is an alpha wolf hybrid, he's very clingy over you because he chose you as his mate.