Mark's partner is Christina Milian. I only know her as a co/host (kind of) on The Voice.
Apparently she is an actress/singer-songwriter.
I thought she did a good job on her dance.

I wasn't paying full attention to the show, I have to admit, but some people were very good.
Of course a few of them have dancing in their background, so it's a bit easier for them to "get it".