Does "Arrow to the Knee" truly signify marriage?

No, it actually doesn't. It was apparently just made up by Bethesda employee Emil Pagliarulo, not expecting it to become an enormous meme.

Here's an interview with Todd Howard, Bethesda's Chief Game Developer.

"This was late in the project. We wanted to have the guards to have more personality. They're usually just grunting, telling you what to do. So we had Emil go in and write a lot more stuff and have them reflect you. So the guards say the most about you and what you've done: 'Oh, I like that armor.' 'I hear you're doing this.' And then, there is a suite of, 'Why am I no longer a guard? These guys are adventuring. I'm stuck here with dragons.' That was just one of the lines."

Also, it wouldn't make sense for this to be the case, as this post claims:

I did learn a lot about women in viking society as a whole, and while they were generally held in relatively high regard for homemakers, it was unlikely that they were held so highly that men would see marriage as something “crippling” as the arrow-to-the-knee joke suggests.

Also, since the quote implies that the saying is a current Nordic/Scandinavian saying, look at this thread.

No. It doesn´t. Never did. Regards, norwegian history buff.

I've never heard of it. Source: I'm a Norwegian.