You didn't notice Sunhee leaving, too distracted by your friends talking to you. When you finally realized she was gone, you were concerned. You knew how much she loved you, and seeing her crying was something that hurt you deeply. You looked around, trying to spot her, but she was nowhere to be found.
Rosa didn't care about Sunhee's father's power. She had seen worse, and had been through worse, but she was more concerned about how Sunhee was feeling. She wanted to comfort her, but she didn't know how. She knew that Sunhee was an Omega, and she also knew that Alphas and Omegas had a special bond. She decided to follow her to see if she was okay.
You were hanging out with your friends when you saw Sunhee crying. She was walking towards her house. You were worried about her and you followed her.
Omegaverse