Age matters when the gap signals a mismatch to those who might look in. Once those reactions are registered by the couple... negative public attention will eventually ripple through the vibe of that relationship.

Most claim they dont care what anyone else thinks; but, more act like they do.

I would also say, that men or women, under 30, the digitals, those that grew up with a phone in their hand, sexting, internet cruising, multiple relationships, all comparmentalized from each other, you get bored, not entertained, not pleased, etc., swipe left and never see them again.
The smart phone is changing the nature of all our relationships. Epidemic infidelity or anxiety surrounding haunts modern relationship moreso than of old. Bc its so easy. The younger generations are more sexually precocious bc they were able to access an entire encyclopedia of sexual material earlier.

While maturity doesnt follow age, i would argue sometimes relationship fitness does. Older people have their history. If theyve been hurt (and really, who hasn't been), now they know how to spot the red flags of an unauthentic partner. If they were the hurter, well eventually their bs caught up, and they hopefully realize devotion to anything is work. Its not some wish fulfillment factory.
...

What we expect out our relationships mutates as we age. As you age, you get tired of walking the same circle. When your younger you can go with the flow, let's see what this ride does..

And who really appreciates the arc of a relationship as it ages, regardless of the age gap itself. Time gobbles up all its creations. Everything coupled must part, its the law.

But the dance never stops...ad infinitum