Children are jealous of anyone who interferes with the attention they get from the person they count on the most. As they begin conscious thinking about themselves and the world, they are focused on their own survival - not in those terms, of course. You could say that their biology preps them to stay in a safe place. In a year or so, she may prefer her dad and want you to go away. It is hurtful, but each phase will pass. It doesn't mean she doesn't love her dad.
If her dad does more of the care of her, she will depend on him, as well. Children gravitate towards the person that takes the most care of them, especially the vital care, such as food, milk, changing diapers, taking care of them when they are sick, getting up with them at night. Depending on peoples' work schedules and responsibilities, it is often difficult for parents to share these tasks equally, but it would be good if they could.
Remember kids think up all sorts of ideas that are products of their imaginations, also. My friend's daughter was afraid that her parents weren't her real parents, that aliens had taken over their bodies. LOL