Edit to be clear the spoilers below are referring to S1 of 'Love' in case someone clicks them without realising.
Dunno, I don't really remember too much detail now but
the difference really seemed to be that Mickey's mistakes came from an entirely reasonable place - i.e. bad previous relationships and a lack of self esteem, while Gus just acted like an arsehole a lot. Magic is a deeply misogynist world at the best of times, but in general it felt like the show thought it was fine he'd made an effort to take her on a date without him seeming to have noticed he treated her badly, e.g. he was more concerned about watching the show than the fact she was freezing cold.
And subsequent to that he doesn't really apologise and the show never seems to imply he should have. Afterwards he just chases some other woman and then gets angry when it blows up in his face.
I mean yeah, having a go at someone at their work is bad but, again, it seemed like he brought that on by going into a massive sulk and no communicating. But once more the tone of the show seems to be that Mickey is in the wrong and so at the end she seems to be apologising to him.
I mean this is the problem: the show is written by the main star and so it just feels like a shameless attempt by him to write a personally aggrandising plot, in my view.