Yes, I'm talking about Wagner's Bridal Chorus (Here comes the bride, big fat and wide...) and Mendelssohn's Wedding March (from a Midsummer Night's Hallucination).
Gary Penkala at CanticaNOVA Publications has a very good take on these two marches and why they're discouraged in many parishes, and even disallowed in some. I usually try to discourage it, and I have in my last three parishes with a 95% success rate. I've very rarely had to bite the bullet with this one (DAG NABBIT! If I was only so lucky at funerals with discouraging Beagle's Things, Be Not Afraid, How Great Thou Art, and Gentle Woman!).
In fact, the rubrics call for the Entrance Song - yes, something sung by the congregation, as opposed to the big march (my most popular option for marches, btw, is putting the Clarke Trumpet Voluntary, aka The Prince of Denmark's March, and the Purcell Trumpet Tune at the front and back ends of the Mass respectively). I rarely get to enjoy the hymn option, though I've had a couple of instances where I've gotten to do BOTH - the march while the party is processing, then the hymn as the couple approaches the edge of the sanctuary (or in some cases, the altar rail).
The late Fr. Rene Gagne, who I worked with for 6-1/2 of the eight years I was at Precious Blood Church, was a big opera buff who would not think twice about travelling from Woonsocket, RI to New York City to see a good opera. I can't remember which opera, Wagner's and/or Mendelssohn's, but Fr. Gagne did mention to me that in at least one of them, the bride featured in the respective march was a prostitute. I often use that defense for my discouraging the two. But now with Mr. Penkala's reference to the groom in the Mendelssohn turning into a jackass, now I think I might have some more clout! Thanks, Gary! :)
PS: I say all this with all due respect to Felix Mendelssohn, who has excellent sacred works in his catalog.