As the previous commentor said, Next.js or React Native + Expo may be a better option. There's also the options of AssemblyScript + React/Next.js, or NativeScript and Ionic, both of which give you mature ecosystems of tools and close-to-native experiences. Flutter, you're likely to have the same experiences you had with Swift and Kotlin. Flutter requires higher separation of concerns between platforms, doesn't have nearly the third-party support of any of the other options, and is fairly large in binary size. Still, it's a growing system and in the future it may actually outcompete the other options when it has a large enough ecosystem.

We have experience with React Native, Flutter or Xamarin, the lion share of the native cross-platform tools used. They all allow you to create very good user experiences. You can check their reddit pages to see the beautiful designs people recreate. I highly recommend using cross platform tools vs native if your app has generic functionality that doesn't use advanced functionality of the app like VR/AR. So, for something like a dating app without those features, you would probably be better off with cross platform native instead of single platform native (swift/kotlin). If budget is low, a lot of companies have success just using Expo (a framework on top of React Native). It limits you further, but it's the easiest and most affordable to find developers with. Eventually you might decide to move away from it, but at that time ou ll have a lot more money and react native will be an easy tech to move towards.

Xamarin is the oldest of the cross platform native tools and so there's a lot more documentation and supporting libraries.

Flutter is super fast & fluid, and since it uses pixels(skia), it's even more performant than all the other technologies including native single platform. But it doesn't come with the amazing libraries that Xamarin and React Native is able to leverage