If you have dreamt of a chain, then you are in a strong position in your life at this time. Something is being secured, and very strongly. The message is that you or your possessions and resources are safe.
A chain represents binding, a pulling together and fastening or two variables, objects, or parties (metaphorically speaking). Thus, there is opportunity for great stability and security right now.
If you feel that this relates to relationships or a relationship in particular, the message is that your relationship is safe. It is strong, and nothing can break it, for you are in a wonderful position. If you are looking to tie the knot and get married, move in with someone, or take your connection to the next level, the presence of a chain is here to show that the universal consensus is a YES. Go for it!
