My mother raised me to say "congratulations" to a groom but not to a bride. One used "best wishes" or some other platitude to the bride. Mom said that to say "congratulations" to a bride was an insult.
Therefore, based on my mother's criteria, the OP was actually being properly polite.
This is correct. Congratulations was said to imply that the bride had bagged a man.
That seems like a rather sexist notion.
It was a sexist notion--which is precisely why it was considered rude to say.
But when it came about, that was actually the truth--a woman getting married was exactly analogous to a guy landing his dream job. She now had someone who would provide money for her, etc.
But to congratulate her would acknowledge that ugly truth. That's why it was rude.
it also implied that she was *lucky* to be getting married, as if she had to do something special to get anybody to marry her. Rude to imply to a woman, especially since she really couldn't ask someone else.
But not so rude to imply to a man, since he was in the position of supplicant, and there's sort of a cultural bias that men are not necessarily automatically appealing. (For one thing, he can make up for being unappealing by being able to own property, etc.) So it's OK to imply that he's lucky anybody wanted to marry him. Because he didn't *need* to get married.