The divorce rate is abhorrent, but the thought of the government being able to force two people to stay together is just as bad. There will always be circumstances where divorce is, in fact, necessary (like when the relationship turns legitimately abusive and dangerous for one or both partners).
I think resisting pushes to make marriage about short-term personal satisfaction and validation (e.g. same-sex “marriage”) is a big step in restoring the culture’s reverence toward marriage.
“the government being able to force two people to stay together is just as bad”
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No one forces anyone to get married in the first place. There are far too many casual marriages. Illegalizing divorce would make people give marriage a great deal of thought (and prayer).
If you want to truly “defend marriage” make divorce nearly impossible to obtain and make adultery a felony. Divorce and adultery is far more common then gays who want to get hitched.