I don't think there "must" be an age cutoff where people are supposed to stop playing - instead, there's an age cutoff for where people didn't grow up with or have access to computers or gaming.

I was born right on the cusp of video games moving from niche nerd shit and becoming relatively mainstream. I can see that there's a clear gap between friends who game and friends who don't that nearly directly ties to whether or not they played games as a kid. A lot of the time for my generation, that's a socioeconomic division more than anything else. Computers were expensive as a kid, so most of my friends who grew up poor found other interests in childhood and grew up to be adults who don't really play games. The kids I grew up around whose families were more well-off have continued gaming as adults. Maybe less, maybe different games; but in many ways it's like asking what age someone is supposed to outgrow "having hobbies".

The older someone is today the less likely it is they had access to games and gaming, and often the more intimidating they find learning about computers and gaming - and the more time they've had to find some other hobby that they find compelling.

There definitely is a thing in the dating market where some people can be particularly judgmental about gaming. Personally, I've found that is loudest and largest for some of the more ... "serial" daters I know, who have found themselves in relationships with lots of different people and have found that gaming, or identifying as a "gamer" tends to correlate with other bigger issues. There's also the side concern when something that's big in your life isn't something they can relate to - a little like the ultra-fan Sports Dudes where all of every game day will always be booked off for watching the games with the boys.

I think in regards to the dating market, it's less that anyone needs to "grow out of" gaming, and more that adults are more expected to have a mature relationship with their hobbies, gaming included. And given that there are negative connotations about degenerate adult gamers not really grown up, that may be something to keep in mind regarding how you present that hobby and how you talk about your relationship with it.