No a marriage vow is not a right to murder your spouse. I find your up is down, black is white, wrong is right twisting of the tenets of morality very disturbing.
I guess we differ on what marriage means. To me it means medical proxy powers and a whole lot more. I think my wife and I are one flesh. Her flesh is my flesh, her bone is my bone and vice versa. I trust her and she trusts me.