Why do large age gap relationships rarely ever work out?

From my experience, there seems to be way more people who would date someone 10+ years older than people who end up marrying spouses 10+ years older. Vast majority of these large age gap relationships never tend reach marriage. Why? I've met so many people who dated someone significantly older but only to end up marrying someone around their own age

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9 mo
Or could it be because both parties fail to have enough in common due to huge differences in maturity and life experience?
Why do large age gap relationships rarely ever work out?
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