For me, the worst thing for being single is I have to dine alone since not many good restaurants have bars or vibe/ service that accommodates solo-diners.
Here's my input:
Bathalzar: the bar is great, but when it's crowded, it's too intimidating to eat alone.
Mermaid Inn: food is good, but the menu is boring. does not warrant repeated visits.
Oh Taishi (spelling?) on St. Marks: great food. love all the small Japanese dishes. Cheap. disappointing sake selection though.
Of course, there's also Sapporo and LAN...