I think the biggest obstacle to sound, serious marriages is the "soul mate" foolishness. People - mainly women - are looking for their soul mate...the "one" that makes their heart go pitty-pat every time they come into contact, and if that "magic" is lacking, then it's just another person in a long line, but not The One. So they Hook Up, maybe even move in together, but there it stops because both of them are still on the lookout for their soul mate. They don't admit it to one another; their relationship has its conveniences, but that's what is holding off the marriage thing. They just haven't found The One, and they don't want to tie themselves down in case that character shows up later on. They spout phone "isms" like, "we don't need a piece of paper to hold us together," and such, but it's all baloney.
The fact is that if two people are reasonably compatible and have reasonably tolerable flaws, AND THEY WANT TO MAKE IT WORK, then they can make a marriage work. Arranged marriages have been going on for eons. The parents get together and make a match, and the two involved individuals are mature enough to make it work, so it works.
I have known at least half a dozen women with whom I could have made a good marriage (and them with me), and the couple that I loved with all my heart, so to speak, would have driven me to distraction.
What we have, as a society, is a lack of maturity, and our entertainment media (music, films, novels, TV programs) is promoting a sophomoric viewpoint of love and marriage, while mocking the story lines of previous generations as unreal.
And we can all see how it's going now.