My sub is significantly younger than me, there's a 15-year age gap, and people keep implying there's something wrong with our dynamic. We're both adults and we're happy. How do we deal with this?

Age gaps in D/s relationships attract commentary because they activate two sets of concerns simultaneously: the standard discomfort many people have about significant age differences in any relationship, and the additional concern about power imbalance in a dynamic that is explicitly built on power. That combination produces strong reactions from people who are not in the relationship.

The external judgment tells you something about the observers' assumptions rather than about your specific situation. Whether your relationship is healthy is a question about the actual dynamics between the two of you, not about the number of years between your birth dates.

The questions worth applying honestly to yourselves are the same ones that apply to any D/s relationship: does the younger partner have genuine agency and the ability to exit or renegotiate without fear? Is the dynamic built on negotiation and ongoing consent? Are both people's needs actually being met? Do you renegotiate when things shift? If the answers are yes, the age gap is not the issue.

The self-examination is worth doing not in response to other people's opinions but because long-term D/s relationships require regular maintenance, and the specific dynamics that age differences can create, different life stages, different social networks, power differences that exist outside the dynamic, are worth thinking about openly between yourselves.

You are not obligated to defend your relationship to observers who have decided it is problematic based on a number.