Princess Jellyfish is one of my favorite manga series ever, so I'm pretty excited to give Tokyo Tarareba Girls a try! Like you, I'm not around the main character's ages, and I don't really have the same kind of relationship issues, so I was worried about how much I would be able to enjoy this series, but I'm glad to see that it's not hard to enjoy regardless if you can relate to them or not! I'm very happy to see that there's going to be so many more volumes to read through too! I honestly can't get enough of Higashimura's work.
If you're interested in trying out more manga with a similar theme, I definitely suggest looking into
The Whale. The MC of this series only wants to settle down with the guy she loves and to start a family with him, but he's more interested in other girls and not committing. This series is a little more series, and has some nsfw scenes, but it's super easy to emphasize with the MC (which is a huge reason why the series is so addicting). If you end up trying it out, I'd love to hear what you thought about it!
