"Marriage unfaithfulness" is not a term used in the Bible, so one would have to define it in order to determine a biblical answer. Where did you get the words from, and how were they used?
Since you ask "What MIGHT the Bible refer to as marital unfaithfulness," then I would consider what the husband is supposed to do for the wife and fails to do it as unfaithfulness. Eph. 5:25 tells the husband to love his wife as Christ loved the church. No one can do that perfectly, but at least we can aim our (husbands') love in that direction. To point his love away from his wife would be "unfaithfulness" to God's command here.
1 Peter 3:7 tells the husband to dwell with the wife, giving her honor. He should make an effort to understand who she is and deal with her in her weaknesses (the "weaker vessel"). Is it honorable treatment to treat her as a slave, to place greater burdens on her than she should bear, to demean her with controlling commands that turn her into a slave instead of a person made in the image of God? To deliberately treat the wife with dishonor or with less than chivalrous motives is to act in "unfaithfulness" to commands in the scriptures.
These are areas the Bible might consider actions as marital unfaithfulness to the scriptural role the husband is called to uphold. I do not mean to imply that these are the same as sexual sins and worthy of divorce. I do mean to state that these are potential areas of abuse (emotional or physical) that would be considered wrong if they are practiced against the wife with evil intent.