Generally speaking, I'm not a fan. Brennan in Bones has a point when she refutes that she and Booth are "friends." I don't entirely agree since I think friendship--the ability to talk to someone about anything--is one of the most positive aspects of a relationship.
But I do agree with her in the sense that I think that an intimate relationship does, in fact, imply a physical relationship.
One of the best platonic yet physical relationships occurs in The Excellent Mystery by Ellis Peters.
*Spoilers.*
A young woman who was engaged to a crusader from a young age learns that he has chivalrously acquitted himself in battle. But he was mortally wounded, to the point where he can no longer father children. He releases her from the betrothal and enters a Benedictine order as Brother Humilis. She dresses as a young man and enters as Brother Fidelis. (Interestingly enough, as educated monks, they are both put to work in the scriptorium.) She becomes his closest confidant and cares for him. In the end, he figures out who she is and expresses his love and gratitude.
It is incredibly touching--and an entirely physical union. Peters makes clear that some more dogmatic members of society considered an engagement the equivalent of marriage. Julian, the young woman, was instructed as much. She considers them wed and claims her rights to his physical body. She baths him, dresses his wound. He is young (enough) in his forties, but his wound is the type that in that time period will eventually result in weakness and death. In a final act of chivalry, he does what he can to preserve her reputation.
The book is beautifully written. Although disguises are not always believable, Peters establishes the "rules" that allow us, the readers, to accept Julian's disguise. And they prepare us for her husband to glean the truth. In a final act, while they are seated together, he acknowledges the blessing of her companionship. Her grief at his death is awesome (in the old-fashioned sense of the word, heartfelt, and entirely physical).
An excellent marriage indeed!