A lot of amusing thoughts on marriage. Like, now that 'Until Death' is no longer applicable, the rest of the contract should be voided.
Also, the contract marriage. As in, being immortal, we can be married for 50 years, but after that, I will be bored with your shit and in desperate need of some strange.
And some creepy unintended consequences, such as the woman who injects her baby with the stuff, so that he will be an infant forever.