This is a pun on "whining". Dating is sometimes referred to as "wining and dining". They changed the spelling to "whining" because the guy did something on their dates that got tiresome to her, making the dates lousy and causing her to dump him. That something could be whining. No one wants to be around someone who whines all the time. 
She dumped him because of all their lousy dates . After all , whining and dining does get tiresome after a while .