There's a particularly frantic stage to parenthood, when you're outnumbered by people who can't use a toilet reliably and are liable to consider legos a food group. For couples at this time of life, it can be months between getting a babysitter and having the chance to go out to dinner and experience adult conversation with pauses and no spilled cups of milk or juice. I've often told friends going through this stage: it gets better. Being a parent does not mean 18 years of diapers and spills and poorly enunciated knock-knock jokes. When your oldest kids are old enough to babysit, a lot changes. You can get away for a dinner or even a night away from home.
All that is true.
Now I want to spend a moment on the opposite side of that coin.
There's a certain privacy to the stage of parenthood where you can talk with your spouse in front of the kids and they will completely ignore what you're saying. There's a peace to the time of night when you've put all the kids to bed, and you can sit down and be just adults together. Despite all the tears, and diapers, and eating odd things, there's a simplicity to the problems of kids under eight or ten. Parenting young kids can be a big like long term babysitting, and it preserves some of the freedom that was familiar as an older sibling: make sure no one gets hurt and otherwise you're free to do as you want.
One thing that's been hitting me lately about being the parent of three-going-on-four teenagers is that it doesn't really stop. The kids often don't go to bed until we do or even later. And unlike in the early days of parenting, you must not talk about things in front of the kids that you don't want them to hear and interpret according to their own context. On a lot of days, it seems like the only time MrsDarwin and I have to talk privately is the 30 min each night after dinner when we take a walk -- a COVID habit I think we'll keep because it's become so essential to us.
Dealing with the kids problems becomes different to. There's a simplicity to dealing with the problems of kids under ten. Stop fighting. Have some food. You need a nap. Let's do some reading time. Okay, you can watch Phineas & Ferb. At times young kids become emotionally overwrought, but at least in our experience it's always in ways that are fairly easy to deal with (if occasionally loud.)
With older teens, it's not just that some of the stakes become higher, it's also that you'd now dealing with someone who has a emotions that are in many ways adult, but who do not have adult level experience in regulating those emotions. A three year old who shouts, "I'm not tired! Stupid Daddy!" and flails at you with his fists is mostly just funny to the seasoned parent. A teenager who directs sullen rage at you for a couple days is on the emotionally draining spectrum somewhere between a toxic co-worker and a spouse you're fighting with.
Similarly, a young kid who isn't doing their homework is a simple discipline problem: You must sit at the table until you get this done. With an older teen, you could do that, but not only do those kind of tactics not work well with a person that old, but a key point with older kids and schooling is that they are supposed to have learned how to manage their own time. If you manage their time for them, you may get the work done, but you aren't getting the long term goal done. You're stuck trying to deal with the more difficult task of encouraging them to take their deadlines seriously and manage their own time.
In dealing with all this, one can feel rather like the aging Bilbo: like butter spread over too much bread. Even as it seems sometimes like the kids individually feel like we're slow in dealing with the specific things that each of them cares about, by the time that you deal with the needs of each of the four older ones and the more collective needs of the three smaller ones, you have spent a great deal of time. Add that to the fact that we're not as young and energetic as we used to be, and it's a recipe for feeling tired much of the time. It's definitely not the same kind of tired which parents dealing with nursing and diapers stage of life experience, but it's constant nonetheless.