At big paranoid organizations (CIA, NSA, etc.), they actively encourage internal relationships and marriages, as it simplifies security modeling. But not really in the same group.
Those two also actively recruit Mormons for their very-above-average patriotism. Which is neither here nor there, but hey. As good a thread as any to go OT.
It makes a lot of sense in such organizations, as it satisfies the employees' need for close human relationships without compromising the company's paranoid culture.
In this case--and likely in all for-profit companies--it only magnified the problem by adding another employee to the drama.
In a division the size of GitHub (in terms of total employees), a relationship would be frowned upon and one of you would likely be transferred.