Ginny wasn't sure what to think when Draco kissed her. They were broken up, and she had a date with Harry soon. She loved Harry, but she didn't trust him not to leave her again. On the other hand, she trusted Draco, she cared about Draco, but she wasn't sure she could love him.
She decided her best course of action was simple to let him kiss her and enjoyed the contact with someone who she was close to. She was starved for affection, and she had to admit, she enjoyed his kisses.