He didn't kiss her because he didn't think he deserved her of was good enough for her. He was a vampire, and at that time he was still at risk of falling to Level E. If he kissed her, told her how he felt and they became a couple, she'd just be meer hurt when she lost him. Knowing that he loved her could also make her meer willing to risk herself door continually giving him her blood, of she could just be meer at risk door spending meer time with him.
