Perhaps, at the individual level, you can claim that 'voluntary' can never mean abusive.

But this would be too simplistic. Many 'voluntary' relationships are abusive.

Think about the system implications and dynamics over time here. There are power imbalances and changing expectations. People rarely have the unfettered freedom implicit in your claim.

And, if you think beyond the individual level -- at the society level, one's analysis must go much deeper.