[aikinai]

In many cases regarding immigration, any single agent can act as judge, jury, and (deportation) executioner. Again something I learned many years ago and have kept top of mind for my own family.

If you are already married, then you enter the country with an assertion that you have no intent to immigrate, then you soon after apply to immigrate, chances you were not lying are vanishingly slim.

Yes, if you meet after you enter the country, then that doesn't apply to you. That's exactly when it is appropriate to apply from inside the country and stay while your application is pending. That's not what these couples are doing.