Yusuf Zuck was actually a good person at heart, but some of his actions made him seem like a bad one.
When it came to matters of the heart, Yusuf Zuck really didn't want to get too entangled and he abided by certain principles. Apart from the mistake with Miles O'Brien, he hadn't fundamentally wronged any woman.
The relationship with Miles O'Brien, how should I put it, started off as a one-night stand, just a release of a normal man's normal physiological needs. But later, things gradually became more tangled between them, and Miles O'Brien was indeed a girl hard to let go of.
Though somewhat muddled about it, he wasn't confused when it came to other people.
Take Ember Vance, for example; his interactions with Ember Vance started with flirting, with a playful, vengeful mindset. But later on, this silly girl hopelessly fell in love with him.
He had thought about coming clean to Ember Vance several times, but various reasons always stopped him.