【Soft spot】
-Pam had a soft spot for her boss, because he showed up at her art exhibition.
-Ryan had a soft spot for stray animals because he himself was adopted.
-James had a soft spot for Hong Kong, since he grew up there.
Definition: A tender or sentimental feeling
Etymology: Tender feelings toward something.
Other examples:
1. Sports is my soft spot. Please let me cover the Olympic Games.
2. Snow-capped mountains are her soft spot. Every year, she would go and explore one of them.
3. She is his soft spot. So put her lead the negotiating team. This way, he will definitely compromise.