Without love, relationship is a glass needs to be handle with care. It can break anytime. Relationship with love and understanding is like a temple where people involved are Deities. They shine wherever they are. Movie dialogue equating relationship to rubber band doesnt interpret the "relationship" deeply. It can be used emotionally for that scene but not in actual life.
I am not very good in English but I hope this helps you : “ many will say relationship is like mirror once it breaks you can never fix it , but it’s like rubber band where if both person try to pull it gets teared , some ppl will throw the teared rubber band and some choose to re use the rubber band by notting the rubber band again it’s upto you “