Speaking as someone who once was a Protestant and now attempts to show family and friends that Paul states divorce and remarriage is just as wrong as sodomy, I can give you several reasons why they either celebrate it, condone it, or look the other way. I've literally had a family member tell me they knew what the Bible said about remarriage but God told them to marry this divorced person. They will respond to the tune of "How can two people who are so in happy in love be wrong in God's eyes?" It would cause them to have to possibly be seen as an hardliner who does love as God commanded. They simply believe once you are saved you are always saved, unless of course you are gαy. They never knew when Jesus mentioned adultery he was referring to those in second marriages, I get that response more than any other but it doesn't matter because God wants me to be happy so its ok. Lastly they really have no clue about anything in the Bible except the end times are coming and if Jesus were here today he would be a proud flag waving neo-con.
The Baptist church I grew up in used to have the biggest youth group in my area. It was not uncommon to have 100 teenagers on a Wednesday night. Now almost 20 years later they are lucky to have 10, in that same age range, on a Sunday morning. I'm conflicted to whether or not that makes me happy. I guess I'm not, I mean its not as if these people started going to the Catholic church. Lastly I remember when I was a teenager, our youth pastors put us through a program called "True Love Waits." Now I couldn't tell you anything that was said during those weeks but if you had told me that sex before marriage, divorce and remarriage were as bad as sodomy and that I was putting my eternal life at stake for doing either then I would have remembered that, but to say those things would have been mean and to be seen as mean is the most grave sin of all in today's society.