You know a LOT about life and family formation. Sooooo, teach your kids.
You've identified some of their worst problems and no doubt have solutions that would work for you, so teach them what you know.
For your daughter, lots of men DO want good love, home, and family -- she just needs to find one, likely 10-15 years older than she is (for the reason for the age difference, that needs some discussion I omit here). Where to find them? Try some parts of the educational institutions -- look for students or more likely the professors. And, try churches and their young adult groups. Volunteer in some promising organizations and meet men there. Get a job where meeting candidate men is likely. Get some girlfriends and swap ideas and lead with them. Try on-line. And I'm no expert: She should get with some experts.
For your son, let him mature until his 30s, help him do that, socially, financially, in general maturity, and then have him meet a girl 10-20 years younger. If she is 20 years younger, then he will have to date her until she is 18 or so, but that's okay, too (just why needs some discussion omitted here). Mother nature and the lawyers agree: A women of 18 is old enough to get married, have kids, and do well at both.
Then do your best as a grandfather: One of the biggest reasons the US just SUCKS for family formation (which it does, with the birth rate so low we're rapidly going extinct, literally) is that the parents don't get enough help from the grandparents. Or, one of the main ways a woman of 18 can be good at motherhood and marriage is that she has her mother, father, aunts, sisters, girlfriends, etc. all helping her.
I read stacks of books about marriage. Far and away the best book I found was E. Fromm, The Art of Loving. It's famous, highly respected in the clinical psychology community, written in Vienna in 1946 (amazing that anything good happened in Vienna in 1946), is short, is easy to read except need to read it several times and between readings think and compare with examples you have seen in life.
In Fromm, can see explanations of the couple (i) gives knowledge (thoughts and feelings) of themselves (often the most intimate part of the relationship), (ii) care about each other, (iii) respect each other, and (iv) respond to each other. Sooooo, can take (i)-(iv) and have a secret scorecard -- she how well she does on all four! Won't find a lot of really good grades on all four! But all four are easy if really want a good marriage, and often natural, that is, just happen spontaneously, when the feelings are really good. And if do well on all four, will likely zoom to the top 1% couples club. Then have activities, accomplishments, memories, traditions that like a lot, don't want to lose, can't get anywhere else, and that will bond the two together. Do well on those and move to the top 1 in 10,000 couples club. And pay attention to the traditional start of the marriage:
"We gather together to join this man and this women with the bonds of Holy matrimony."
So, there's supposed to be some joining and bonding -- actually a lot of both. It's not supposed to be just a tennis doubles team or two scorpions in a bottle.
A lot of classic movies have some good insight into what makes women tick in love, home, marriage, and motherhood. So, go for
Roman Holiday,
Gone with the Wind,
Father's Little Dividend
https://www.youtube.com/watch?v=DR-OkcqI8NU
and two Hallmark chick flicks
The Magic of Ordinary Days
https://www.youtube.com/watch?v=P8AvLMIElKU
Autumn Dreams
https://www.youtube.com/watch?v=SI-ikF-Bdrg
In each of these, can see where the women are mostly interested in love, home, and marriage and where, instead, they are mostly interested in something else. The last two, the chick flicks, make this interest dichotomy really clear -- the women start out with biggie interests OTHER than love, home, and marriage and, at the end of the movies, as they achieve success, they are putting love, home, and marriage first and the other interests secondary or lower. So, the suggestion is clear: She was going for a Ph.D. but that was largely INSTEAD of love, home, and marriage, and when she got love, ..., the Ph.D. was set aside. There is a hint, can debate, that a women going for a Ph.D. does that because she is NOT doing well with love, home, and marriage -- again need to debate that point, but the movies seem to have a clear position.
So, in these movies there is some art as in "the communication, interpretation of human experience, emotion" with some good examples but also a lot of ambiguity. But if watch them all and compare and see what is in common, then will begin to see some of how women tick. Your son should do that. Maybe have him write some essays on what he concludes about women. After each movie, discuss with him the lessons you see in the movies about women. Hollywood is this and that, good and bad, but on some things, especially how women tick, the best of Hollywood, IMHO is just terrific, some of the best there is. I never cease to be amazed at the directors who were famous for directing women in movies -- how the heck they knew so much and got it up on the screen so that even naive boys could understand it. To be a husband in a good family just MUST have some good understanding of females, for the wife and the kids, the daughters and what teach the sons -- hint, as Fromm wrote: "Men and women deserve equal respect as persons but are not the same". Expert grand understatement of the century.
Why need to understand? Because due to parts of the economy, transportation, and more the old patterns that DID work have broken down. Now largely have to build starting with nothing in norms, expectations, traditions, etc.