Should Marriage have a Sexual Contract?

You mean, as in: “Sleep with me, yer lazy bastard or I’ll sue you!”?
Well, that’s exactly what a French woman did; she sued her husband for damages because he hadn’t slept with her in 11 years.
The appellate court in Aix-en-Provence last year awarded the woman 10,000 Euros in damage payments.
A marriage is by definition a contract between two people and includes the obligation to perform sexual duties.
To willingly and gladly perform these marital duties, as Germany’s Supreme Court ruled, not just in a perfunctory and victim-like-near-death style!
Marriage in all cultures has a sexual contract built in but in my experience it is not really easy to enforce it in the home on a daily basis. (Marital rape is a crime so what are you gonna do?)
You can always threaten legal action as not performing one’s sexual duties is sufficient grounds for divorce.