I don't want to share my salad with my mom.
That sounds mean. Why wouldn't you share the salad with her?
I love her but I don't want to share salad with her.
Even if you love someone, that does not mean you are required to share everything with them. If you want to share your food you should, but you should not feel guilty for eating your own food yourself.
I don't need to give an explanation to anybody about what I do with my food.
You are right. It is your food and you should be able to decide what you want to do with it. Some people like to share, some don't, it is okay if you don't want to share it.