Reassure your daughter of your love. The insecurity you’re describing makes us also think of jealousy; these two are related to each other. When your daughter is insecure of the love you have for her, she can start feeling jealous when she sees you displaying affection towards other people. She may have unrealistic expectation that she wants this only for herself.
Insecurity and jealousy are very natural reactions. As preschool children are often in touch with their feelings, they may display these with little hesitation. They may throw tantrums, show aggressions, and exhibits behaviors. Some may identify with the person they are jealous of (e.g. imitate the behavior of a baby who sleeps in a crib). We can sense your frustration over her extreme reactions. And your exasperation can easily translate to disapproval and withdrawing your affection whenever she shows these insecurities. We suspect that the more you castigate her, the louder her tantrums get. If this is so, then she must be throwing these tantrums to try to get what she wants: reassurance that you also love her.