restraining order among upstairs and downstairs tenants

We own a house with two units. The downstairs tenant has complained about the upstairs tenant, although I personally know she has made such complaints before about various tenants in the past and has a propensity toward not getting along with people. She just obtained a restraining order against him. What are our obligations as landlords? We can't just evict the upstairs tenants based on that in the state of WI. Thanks.

[OHlandlord]

Tough question. You may have to consult an attorney to see what your obligations are in this situation. At the least, I would send a strongly worded letter to both tenants not to interact with each other, given the present situation. Unless there is more to the story here that posted, the downstairs tenant seems to not be able to get along with others well. I would find a way to move her out at the end of her lease if she persists in this attitude toward other tenants.