Kaori-Oh, well.... i don't have experience with..... such things. But I'm still a girl, so maybe i can understand a little. I don't really know Sakura-san personally, but based on her stoic attitude, and the fact that i am aware of.... certain rumors. I think maybe she's been lacking affection from other people, aside from family. It may be a mechanism to reaffirm her and your love for each other. She may just have very low self esteem. After all she is rather short for her age, so she might think you just put up with her appearance while you seek out women with, uhm..... mature, bodies. So maybe it's her way of keeping you interested in her, and making you happy?