Do you think Cho would succumb to abuse (all kinds) by the man she loved? Do you think she would defend him; saying he surely doesn't mean it?
I don't think Cho has involved herself in any abusive relationships up until this point in the HP series. Harry and Cedric weren't abusive towards her, and I don't think she'd gravitate towards someone who had those tendacies. However, people can be deceptive, so if she found herself with someone unsavory, I'm not sure she'd stay with him. She walked away from Harry when he was being a jerk, didn't she? Why couldn't she walk away from a man that was legitimately hurting her? I don't think she would defend someone who she knows is doing wrong
I think Marietta's betrayal only proves my point further- Cho is loyal to a fault. I think that Marietta's betrayal was horrible, for she gave up her best friend as being against the laws of the Ministry, and yet Cho stood by her side, showing that she's loyal, even to those who harm her. The relationships between best friends and husbands are similar in strength, though I think women tend to hold to romantic relationships(those resulting in marriage) more fiercely than those between best friends. If she would defend Marietta even when betrayed, where is the proof that she wouldn't do the same for someone she felt she was in love with?
However, with Marietta, Cho shows poor judgement in her friends. Marietta, despite her betrayal, was on the 'good side' for a time, and I think Marietta's betryal shows more of Umbridge's power over the students, even those in the DA, and the weakness of the individual under so much pressure rather than any failing of Cho's. But because Cho defended Marietta, she may be inclined to defend those people who do wrong things for the right reasons.