Okay, suppose they don't get a restraining order, but use their perogative as blood relatives to instruct the hospital not to admit the partner. You're ignoring the underlying issue here. And I know a divorce attorney, and I've heard some stories about restraining orders that would curl your hair.
Then I would say the life partner who got sick was irresponsible for not providing for this enventuality and ask you this question" If this person was so irresponsible over this small issue regarding his/her relationship,. what makes you think he/she would take the responsibility marriage would require ?