Actually I don't see why he had to tell Korra, that he had a kiss with Asami after he broke up with her. They weren't a couple anymore, so he could do whatever he want. And Asami... please, she was so the one who kissed Mako after he broke up with Korra after about two days. Sorry, but I really can't feel sorry for that bit**. I thought she was/is a friend of Korra and friends doesn't to something like that! She can't expect that Mako can forget Korra so easily and quickly. Besides, she kinda pushed Mako in this situation. After he didn't reject her kiss at the first time, she should have knowen that he's really not ready for a new relationship. She really got what she deserved and I hope she finally knows that Mako doesn't and never will love her.
And Mako really regain his honor by broking up with Korra. He didn't want to, but he knew that he had to, to fix it all. That's why I'm still thinking, he and Korra can become a couple again.
Don't take me wrong, I was also pissed in first time. But when I took a second look of the whole situation, I could see that it wasn't that bad.