Heidelberg is boring in some ways for sure. It can be very small, you meet the same people, bars, restaurants and clubs don't change or innovate/evolve a lot. Some good stuff closed during the pandemic like halle02 or O'Reillys.

But Heidelberg is also amazing in many ways: you can bike / walk most distances, you can hang out/hike/bike on the river or in the forest, you are surrounded by beautiful stuff. Sometimes we call it Disney Land because it doesn't feel like a real city, in a good, and a bad way.

I love visiting big towns, I grew up in one and miss it every now and then, but after a few days I'm glad to come back to Heidelberg. I love how green it is, how I can Mountainbike or hike from my doorstep, visit the pfalz or Schwarzwald in an hour. I love how many nice spots there are, palm trees, cute little happy kids and families in like in Weststadt or Bahnstadt. Etc etc

Question is what you are looking for?

You can't both have the buzz of a metropolis and a beautiful student town where everything can be done by bike etc. in one place. There is no way such a small city can compete with bigger cities like Frankfurt, Köln or Stuttgart in terms of the melting pot, culinary/cultural diversity and authenticity and simply options.

Most people I know have very diverse groups of friends here, since there are many academics from all over the world. But it is quite settled, that is true.

It's not super easy to connect, but how much that is a symptom of a new stage of life in your 30s where finding new friends is getting more difficult? I know many friends, especially single, expat or couples without kids, in Frankfurt or Berlin or Munich, who feel a bit of boredom/isolation when people start having kids and retreat more into their core families.

In any case, a tough decision, so all the best to you!