if they are married just for convenience, they are committing fraud, which in itself is a sin
examples would be:
marriage just for tax breaks
marriage for citizenship
I think it depends. For citizenship I can’t speak but on the tax/fiscal side I can offer an example where I don’t think it would be a sin.
There are relationships of mutual co-dependency out there that should have some kind of tax or different fiscal treatment similar to that of married folks. A case in point was my mother and elderly aunt which I spoke of on the same-sex marriage thread. They lived together for 30 years after my father died as my mother was in frail health and could not work, but her spinster sister had a decent job (and eventually a good public-service pension).
Because they weren’t married my mother had no survivor rights to my aunt’s pension should she die first (a real possibility given that my mother and aunt lived to be 83 and 92 respectively and died within a year of each other).
They were mutually supportive of each other. If my aunt had died first (she died after my mother as it happened), and didn’t have me for support, she would have been left destitute.
It’s unjust that a same-sex couple can get these rights on the basis of a
sexual relationship but my mother and aunt couldn’t on the basis of a sibling relationship.
However I do know of some sexless heterosexual marriages, generally second marriages where the couple are too old for or are no longer interested in sex. Yet they love each other, are great friends, have a relationship of mutual co-dependency, do activities together, and present themselves socially as husband and wife.
While the Church won’t recognize this as a “marriage”, I personally have no problems with couples like those undertaking a civil marriage or union. In fact it is possibly a matter of survival for the remaining partner should one die, and is the only way to ensure survivor benefits.
In Canada these benefits are important. If you are not married in Quebec, for instance, your RRSP (equivalent to 401k) is fully taxable on death of a partner, but if married, the RRSP is transferred tax-free to the surviving spouse. This can represent hundreds of thousands of dollars. Secondly, as mentioned above there would be no pension survivor benefits.
I don’t think you can say that a mutually co-dependent but non-sexual couple are committing “fraud” or just “convenience” by taking advantage of legal mechanisms provided by the state to protect survivor benefits.
Therefore I think that for legal unions outside the Church, the guiding rule should not be a
sexual relationship, but rather a relationship of mutual co-dependency.