I think it can be incredibly hard on many levels. What I've seen...the student is aware of their own stress, is focusing on the long-term rewards, and as such, neglects the aspects of their life outside of law school, expecting the spouse/partner to pick up the load. When that happens, and the student is forgetting how much their partner is sacrificing, the partner can become resentful that their needs/wants have taken backseat.
If the student is careful not to let that happen (the other person taking a backseat), contributes as much as possible to household chores (even if it's just half an hour a day of straightening up, doing dishes), and generous with the appreciation, I think it'll be fine.