Give them a month. If not there after a month, contact them at the 1-800 number. See quote below from the romance rewards page on the website.
"Three night minimum stay required to receive benefits. To receive credit for your stay, provide your Romance Rewards number to the Front Desk prior to check-out. Your account will credited 30 days after check-out. Duplicate registrations will be cancelled. It is guest responsibility to verify accuracy of their account. You have up to 12 months from the travel date to contact us and request an update. If the nights' balance on your account is incorrect please contact us."
It should be there already. It's supposed to be applied at check-out. Either call Couples, or click on the Romance Rewards Coordinator link under the Romance Rewards page, and you'll be given a form to fill out. Provide the details of your stay and your romance rewards number. They'll get it taken care of, but make sure you get a response confirming that.