He hoped she had forgotten him--forgotten and moved on.
Rabastan lost too much in Azkaban to recall her face in his memories after so many years. Dementors stole Jocelyn from him and at that point in time, he was not willing to start over again. The war reached a critical point and now was not the time for Rabastan to dare ask Jocelyn for her affections--albeit she offered them to him.
Meeting her eyes after a long moment, he longed to hold her once more, to kiss her. Rabastan took a step back and walked further into the garden, stopping at a large fountain. The glow of the moon reflected off the water and lit up his face. "It's been fifteen years, Jocelyn," he said, leaning against one of the stone tiers. "I'm a different man now. You will find your affections for me have changed, whether or not you want to let go of that. Azkaban took you away from me, the dementors took memories of you from me. I had forgotten what you looked like until you stepped into my house. I've--I've got mental and physical problems that I'm struggling with. I want you to be happy, Jocelyn, and I cannot make you happy."
Not right now. Not during the war, he thought as he closed his eyes. Rabastan turned his attention up and faced the night sky, watching a bird of prey fly off in the distance.