generally, you say 'I'm sorry' when someone dies, you say 'Please accept my condolences' what is the 'sad event' that you have in mind?

"I'm sorry to hear that" is a perfectly acceptable (and respectful) phrase.

Commiseration!

I am sure Mohamed will remember that the word "condolences" is used when someone dies. If your national football team loses or you break up with your girlfriend, there is no need for others to send condolences.

Officially, 'condolence' is the opposite of 'congratulation'. "My condolences." is a very formal way of saying it. In common lanuage, though, "I'm sorry for your loss." or just "I'm sorry to hear that." are preferable.