Marilyn Manson Cupid's Bitch

Even the Anti-Christ Superstar is a sucker for romance ... at least on Valentine's Day.

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TMZ caught death-obsessed goth-rocker Marilyn Manson leaving a very lovely -- and very expensive -- V-Day dinner at Nobu with a mystery date Saturday night.

After the meal, the man who took his moniker from a famed murderer, was nothing less than a perfect gentleman -- chivalrously escorting his lady into a waiting ride.

Somewhere, Satan is seriously jealous.