Maladaptive schemas are pervasive self-defeating or dysfunctional theme or pattern of memories, emotions, and physical sensations that we tend to develop during childhood. It is a belief we hold about ourselves or the world and can be very disempowering to have to live with.
One maladaptive schema many people suffer from is the Abandonment/instability. Holding this schema makes a person feel they will be abandoned, that significant others will not be able to continue providing support, connection, strength, or protection because they are unstable, unpredictable, unreliable; because they will eventually die; or because they found someone better.
We may build this belief because in a time when we were dependent on our parents or caregivers they were not present, physically or mentally. From there we feel we can't trust others to look after us and we feel at anytime the ones we love could leave us or abandon us. We never really develop an innate sense of safety around relationships.
We may become clingy in relationships, jealous, controlling and possessive, all which are attempts to hold on to the person we are sure will abandon us.
But what is important to understand is you are no longer that dependent, needy child. You are capable of meeting you own needs and being the rock you depend on. It is important to understand this because through this you can learn not to be so afraid of people leaving you. It is the feeling that you will not be able to cope that you are afraid of when you fear people leaving. Learning you can cope is the first step to not fear a person leaving you.
A second thing you can try to do is look back into the past and see those memories of people abandoning you through the eyes of an adult. Try to see the situation as it was. As little kids we draw sweeping conclusions, we decide if mum was late picking us up she can never be trusted and she doesn't love us anymore. But maybe she was just busy that day. Seeing the situations through the eyes of an adult can help you see that the conclusions you drew about people not being there for you were not based on fact, but on a little child's imagination running wild!
And thirdly accepting sometimes people wont be there. And thats okay. People are human, they make mistakes, we cannot always depend on them, they let us down. But that doesn't mean we can never trust them or they will always let us down. People are just people. And you are capable of looking after yourself.