I'm really not sure when the event ended... First, it had the end of day switch for me [from east coast US midnight (-5) to west coast US (-8)] after I started the first mission, then it unexpectedly gave me cupid when I completed the 13th mission (not after finishing the 12th, not when event ended, when I finished mission 13 and started mission 14) {that may have been after 12:01 am in Japan on 2/15, I've always had trouble determining what the proper date is for Nutaku challenge purposes- even the countdown timers are off 1/4th of the time}