Dreaming trapped inside a cage is a sign that the person is in an oppressive marriage and she finds it difficult to escape. The cage symbolizes a wrong relationship or marriage that will eventually enslave you.
People marry for different reasons, and sometimes we make the wrong decisions while choosing a life partner. As a result, most people end up in the wrong relationship and marriage, which in turn puts their lives in bondage.
The dream reflects a person who made the wrong decisions regarding marriage, which now has become a thorn in their flesh. Probably, they are in an abusive relationship, but they can not escape it, as the marriage covenant itself prohibit them from doing so, hence it has become a trap and cage. Or maybe there are children involved, and despite the marriage being oppressive and abusive, the person finds it almost impossible to escape from it. The wrong marriage is a life cage.