When you’ve been married for more than half a century, you learn a lot about how to make a relationship really work. Boston Mayor Marty Walsh hosted an annual party last week to celebrate couples who have been married for more than 50 years, and they shared some of that wisdom with WGBH Radio’s Craig LeMoult. It turns out there’s no single secret to a long and happy marriage. But it helps if you have a sense of humor and patience, and put down your phone so you can actually cherish moments together as they happen. And no matter what happens along the way, they say, just keep going.