Responses
As for Seo-In, he'd set-up the relationship with Hae-Yool in order to flush out HaeYool's sponsor, who happened to be Seo-In's cousin and CEO of All One Entertainment. So....HaeYool already has a sponsor (u know, someone he sleeps with to get promotions and endorsements) but he also likes YeongWoon and so he tried to catch YeongWoon's attn by setting up a relationship with Seo-In. But it backfired because his sponsor got flushed out and he inadvertently ended up connecting his manager YeongWoon with his long time first love.
I am glad that the pace of the story is good. I think Yeonwoon liked the model guy but could never accept how he felt so in order to make him realise this the model guy did something. Probably a fake affair with another guy. Also i think Soe Hae yool (the actor kid) has feelings for Yeonwoon. It's just a theory but let's see.