Mary and Marshall in “Unfinished Business”

Mary

I remember when I was seven, almost seven, I remember asking someone "what's the point of a partner if you're just going to do it yourself?" My whole life I think I haven't understood that word. Not really. I don't know. I just know a partner doesn't leave you on the doorstep; he follows you there, even at four in the morning.

Marshall

I wonder what you're dad would say about that.

Mary

The same thing he always said: never trust your partner.