Age is most important in a healthy relationship because I think understanding each other develop through age consequences. A man in a relationship can better understand the partner feeling and their situation. Both can tackle situation very easily because they understand what's right and wrong.
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They make the decision and any type of things handle very carefully, that's why age is matter in that case where a husband & wife or in friendship both easily keep relation to lasting forever. Both are live life-friendly and makes good understanding each other on anyways.