Is Sansa and Tyrion's marriage still legitimate?

Question

As of the end of Season 6 of Game of Thrones, it seems very likely that Daenerys and her fleet/army will, at some point, come into contact with Jon Snow and the North. It's entirely possible that they'll become allies - they both want the Lannisters removed from power, and they have a mutual friend in Theon Greyjoy.

As Daenerys said, "The best way to make alliances is with marriage." I know there's been a lot of speculation about a possible marriage between

Daenerys and Jon.

But what about the fact that Daenerys's Hand of the Queen has already been married to Jon's sister? And the relationship between Tyrion and Sansa, while not exactly loving, was better than how Tyrion and Shae's time ended, and certainly went better than Sansa and Ramsay's marriage. So the two of them might be amenable to the idea of marrying for the sake of their respective factions.

But a lot has happened since then - Sansa was married to Ramsay, and Tyrion was convicted of murdering his nephew and fled the kingdom after killing his father. And the lords of the north might not be so keen to kneel to a Lannister. If the marriage is no longer seen as legitimate by the populace then it would defeat the purpose of sealing the alliance.

So my question is: Assuming Sansa and Tyrion want to resume their marriage, is there any law, custom, or precedent in Westeros that could prevent them from doing so?

Answer 1

Source: Wiki of course, where else would we get our knowledge?

The Books

The Wikia page states that a marriage can be annulled if it is not consummated, this can only happen by request and must be approved by The High Septon or A Council of Faith.

That means that a marriage is not automatically invalid if not consummated.

The TV series

In the TV series it is stated many times that the marriage between Sansa and Tyrion is not legit because they did not consummate it. Most of the times this is said by the people who want to marry Sansa to someone else or benefit from their lack of marriage.

If the TV series would follow the rules of marriage of the books, then Sansa's marriage to Ramsey would not be legitimate but her marriage to Tyrion could be.

The information of how an annulment would work could be kept as a plot twist for when the 2 characters meet again.

Or the TV series has already given us all the information about marriages and thus not consummating the wedding automatically annuls it, if we are to believe what has been said by (for example) Littlefinger.

In that case, Sansa is now a widow.

Extra

The wikia also states that women, who are forced to marry while being a hostage (not to be confused with simply being forced by their parents) can also ask for an annulment.

So Sansa could still ask for an annulment because she was forced to marry Tyrion.