For example in the course of people saying that marriage limits their freedom, that the years of fun are over after it etc. Especially in progressive circles it seems to be frowned upon and it's regarded as boring and unprogressive if people marry early. It's probably also losing value as people become more secular and the concept isn't tied to their world views as tightly anymore.
On a more general note, I have the feeling that we are losing other useful cultural mechanisms over the course of secularization as well, and we are right at the transition where both spiritual and scientific explanations are regarded as unacceptable. I'm however still hopeful that the work by philosophers like Sam Harris and Daniel Dennett can help us building a value system based on naturalism.
As someone raised in an environment that was centered around religion (commune-style, basically), I often worry about how our secular environment will develop as the religious underpinnings of our culture fade away. Our approach to long-term relationships is one thing that sometimes worries me, as is our approach to community-forming.
But as an optimist and a fan of change - change in general, even if it's sometimes bad - I'm really excited to be living in a time where we are free to rediscover and rebuild our world. I hope we can figure out how to keep the things that worked, and find replacements for the things that didn't.
On a more general note, I have the feeling that we are losing other useful cultural mechanisms over the course of secularization as well, and we are right at the transition where both spiritual and scientific explanations are regarded as unacceptable. I'm however still hopeful that the work by philosophers like Sam Harris and Daniel Dennett can help us building a value system based on naturalism.