Rimontastique

I’m looking for a BL manga set in an Omegaverse. The story follows an omega who is a model or a public figure, often in a bad mood, and wears a collar out of fear of alphas. An alpha begins working for him—I can’t quite remember in what role—and over time, they grow closer and eventually fall in love. In the final chapters, the omega gets the opportunity to model for a designer who creates collars, including the special wedding collar for him.

There was this shoujo manga where a girl blindly trusts her boyfriend but he ends up cheating on her with her bestfriend. Then the best friend's boyfriend confesses his feelings to her. Do any of you know its name?