You heard from me last night in the forum, but to put it here as well (for that extra credit), loving someone is not something you turn off and walk away from when things get tough. At least, not for me.
Your professor stated that people require sex and/or companionship and therefore could not sustain a one-sided relationship with a loved one in a coma. Either your professor is playing devil's advocate, or is a hopeless cynic. If the latter, my deepest condolences.