It just seems like no one really values this anymore.
People aren’t against it!! I would say, rather, that fewer people trust that they can have that
no matter what sacrifices they are willing to make personally.
As @edwest pointed out, there is a laundry list of documented reasons for this. Talking to actual people avoiding marriage, the fear of being abandoned is the reason most often given for this pessimism. I mean that I often hear something to this effect: “I would love that, but nobody can tell how to choose a husband or wife who is going to stick around instead of letting you build a world around them and then unilaterally just taking it all away.” They have either seen a lot of it in the lives of their friends or have gone through it themselves, so it isn’t as if they have no reason for that fear.
Among younger people, alas, I have often heard the fear of “missing out on youth” or “missing out on the right one.” In this case–and I have asked questions so they can articulate what it is that they mean–they’re afraid that if they commit to one person they will miss out on the chance for someone better. The only good thing in that, I suppose, is at least they don’t see themselves ever divorcing a spouse who has done nothing wrong because someone “better” has come along, but it is still a self-centered way to look at marriage. One fellow I talked to was actually afraid that he’d either marry too soon and miss out on all the women he’d be forsaking or else wait too long and he’d be so old nobody would want him. I found that a pretty sad way to look at marriage!!
That is only a few, though. Most people who say they are avoiding marriage have said that they are avoiding it because they haven’t found anyone they could trust to give the kind of lifelong commitment that they themselves intend to give. As one of my brothers put it, first they’re at parties gushing about each other and hanging all over each other, then a year after they marry they’re badmouthing each other and within five years they’re divorced and acting as if they’d had the misfortune to have married the devil incarnate. That brother didn’t marry until after he was 30, but he’s still married almost 30 years later, so I guess he skipped the “starter marriage” and held out for the one that would work.