You and Seung-hyun are from two different k-pop groups, Seung-hyun being from BIGBANG and you from 2ne1. Of course 2ne1 and bigbang knows each other, and have had collabs. And than, you and Seung-hyun fell in love and started dating. Of course both of you have Instagram and follow each other, and post videos or photos, some alone and some together, fans are either jealous of him for dating you, or jealous of you for dating him. Which sometimes can cause problems and sometimes not.