The choice of who your partner is for partner workouts is big. If you have a partner who is off task, they could pull you off task as well. But also, if you have a good partner, they could push you to work harder.
Personally, I work better on my own. I could see how people could work better with a partner. Maybe when working with a partner they feel more motivated to work harder than them. Me personally, I feel like when I work on my own, I stay more focused and get more done.
Brett's Fitness Blog 