Rachel and Mike's relationship survived Mike's revelation that he never went to a law school, and other minor and major hiccups in "Suits" Season 3. Their bond solidified in the previous season, while the other two couples, Harvey and Scottie and Louis and Sheila, broke-up. This season has been different because of the introduction of Logan Sanders, Rachel's ex-lover. The episode 6 featured the passionate kiss between Rachel and Logan. Rachel is all set to tell Mike about the kiss in "Suits" Season 4 episode 7, which is titled "We're Done."
Mike is already in dumps because he got fired from his investment banking job, as he had betrayed Sidwell. He he did not tell Sidwell about the main stipulation in his deal with Charles Forstman. Mike had agreed to Frostman's condition that Sidwell will not get a penny from the take-over deal.
The preview of the episode suggests that Mike has not taken the revelation about the kiss between Rachel and Logan, calmly. He can be seen warning Logan, "you stay the hell away from Rachel." He seems to have punched Logan, and the latter looks like has retaliated, as well.
Also, Mike can be seen telling Rachel, "We're Done!" when she runs after a furious Mike, telling that she made a huge mistake. There is also a glimpse of Rachel, wondering in front of Donna -- what if Mike does not forgive her. In the past, Mike and Rachel have managed to resolve the issues between them by the end of the day or the episode. This time, however, it looks like Mike will be taking sometime before Rachel and he start talking like a couple, again.
The preview text says "hitting rock-bottom is just the beginning." Harvey is likely to help Mike before he goes back to his old drug dealing ways. And, this time his grand-mom is also not there to hold him back from going astray.
Aaron Korsh, creator of "Suits," has said on Twitter that Mike is "in for more drama."
Official Synopsis of "Suits" Season 4 Episode 7, "We're Done":
"Mike is going to be left feeling stunned following the takeover battle. Rachel is going to share some upsetting news. Jessica is going to allow Louis to name his own reward."