What does "so much for ~" mean? Is it an idiomatic expression?

Native speaker’s answer
Rebecca
Yes it is. "So much for ~" is an expression that indicates something has been disproved or that something is unsuccessful. This phrase can be paired with almost anything! Here are some examples. Ex: So much for going to beach today. It's too cold. Ex: So much for finding a vaccine for the virus. Ex: I can't believe my date cancelled. So much for getting a boyfriend.