The budding love story is a go to for writers. Everyone loves it, and makes you feel emotions when they finally get together. Problem is, it has a natural path.
2 to 3 seasons to get together. 1 season of new bliss, 1 season of ups and downs, ending with a marriage proposal. 1 season of engagement ending in wedding. 1 season of new marriage stuff. Now what?
Married couples are boring. So what do we do now? Now it's time for the baby.
And babies are horrible on TV. People watch TV to escape reality, not hear a screaming child. So the dream couple has a baby and it's so tiring and so much work, but suddenly the show starts focusing on other characters, and then suddenly you know it's over.
The office was famous for this one. Everyone loves Jim and Pam, until the wedding, then who cares. They tried to force those feelings again with Andy and Erin, but you just can't.
Parks and rec luckily took a different route with Andy and April, but you can tell they were teetering on the edge, and in the final season everyone had kids anyway.
HIMYM had a worse approach because it wasn't that Ted was on the path, but rather Lily and Marshall already were and so kids came in earlier, and again change the entire show.
I think Modern Family was the exception to this, at least with Mitchell & Cam. Gloria getting pregnant just had vibes of Married with Children when Peggy got pregnant and it felt like the start of the end.
It worked with Modern Family because the show's entire premise was about Families and when that's the show's premise then the reverse is true, Families without children are boring lol
Married with Children’s pregnancy story arc was driven by the Katey Sagal’s real life pregnancy. She unfortunately had a miscarriage after it had been written into the show, so the writers decided to bail on it by making it all a dream. It comes across as sloppy writing, but it was probably the most compassionate way to handle it.
I was a young teen at the time and that show was part of my Sunday routine for many years, and I remember everyone was curious how the show would handle it. After seeing the episode, I distinctly recall feeling like they handled it very well and would have been disappointed if they'd make Katy Sagal have to act with a baby after going through that. I was also more sympathetic towards Peggy after that.
I'm not sure if that's a red flag as much as it's just a symptom of a show having gone for a while. Like if it shows on the air for a number of years then naturally couples are going to have to start moving forward with their lives so a baby's rather par for the course. However at the same time the longer show goes on the more likely it is to start to decline. I'm thinking this is more correlation than causation.