What an interesting matter! I'm perpetually concerned with the financial-legal ramifications of marriage, how one must be prepared to live with all sorts of unknowables far in advance.
So, on the one hand, the government doesn't allow people to marry only for love, and have only a romantic relationship, but in many regions requires that it become a legal/financial contract as well. On the other hand, as this thread points out, the government also requires the reverse: that people are marrying not only for legal/financial reasons but also for love (or power, control, extended social arrangement, etc).
Geez. Why the crap does it require that two rather dramatically unrelated things apply in one relationship? Those who have found romance with people they are entirely comfortable entering a lifelong legal-financial contract with, where that also works out well, are tremendously lucky, but heaps of people find only one element or the other.
Why wouldn't the government want people marrying "only" for financial/legal reasons?? If this is the system's primary or easiest mode for moving forward in one's life, why in heaven's name does it need people to be lusting after each other or gazing gaga into each other's eyes, too?? And yes, since even "living apart together" marriages are recognized and taxed as marriages, why can't people immigrating do this, too? Argh.