Golovkin is my favorite fighter, but I expected them to give the decision to Jacobs. I'm going to have to watch the fight a few more times, but I believe it was close enough that you can't be mad either way.
I think we saw Golovkin get frustrated by Jacobs' movement tonight. For a large portion of the fight he walked Jacobs down while peppering him with jabs that seemingly couldn't miss. However, he couldn't land the power shots everybody knows and loves him for.
Jacobs on the other hand did land some decent shots throughout the fight, but they didn't visibly hurt Golovkin. He was smart in moving, but a lot of people do view it as running (thus negatively). Jacobs closed rounds out well, but the showboating may have done more harm than good because he couldn't visibly hurt Golovkin. A fighter that fights on the back foot and then engages at the end of the round can be viewed as trying to steal the round. And if you don't hurt your opponent in those final moments of high output it might not be enough to sway the judges.
I'll be interested to see the cards because the punch stats had Golovkin way ahead and more accurate.