There's a tendency to want to interact with people you actually like throughout your day-to-day life. Family, friends, co-workers: all are people you're probably going to have to see a lot. It's that third group that can really cause issues, because there's no blood obligation and you didn't necessarily choose to spend time with them.
The NHL isn't the average workplace, but it's still a workplace. They get to play a game for a living, but it's still a job, and teammates are co-workers. Hopefully they're actually friends, too.
Brian McGrattan seems like a pretty swell dude: the kind of guy who'd be everyone's friend.