This is an awkward situation and I don’t think it is because of a cultural difference. Here it is in a nutshell: He took you out on a date, realised it was a mistake and now rather than just remaining friends is doing what most men do, running. He doesn’t fancy you or see a future together with you. But you know what? He is an ass, a selfish, arrogant ass. You are much better than him. Go to work looking amazing but completely ignore him. Turn your back on him whenever he approaches, get your desk moved!. Completely cold shoulder him too but even worse than he has been doing to you, look right through him, it will drive him mad. If he speaks to you, be polite, of course, always, but never start a conversation with him or be around him. This isn’t a Swiss thing, it’s a personality and ego problem. Best of luck, don’t let him effect your confidence, you deserve better.