Hello Qubits.
Welcome to Apple Support Communities. I understand that you’re unable to love the “Now Playing” song on your Apple Watch. I’m happy to help.
Please use the steps here to restart your Apple Watch: How to restart your Apple Watch - Apple Support
Please, also, restart you iPhone using the steps here: Restart your iPhone, iPad, or iPod touch - Apple Support
Once you have restarted both Apple Watch and iPhone, try to love the song on your Apple Watch.
If you’re still unable to do so, please update your Apple Watch to watchOS 6 using the steps here: Update your Apple Watch - Apple Support Also, update your iPhone to iOS 13.1.1 using the steps here: Update your iPhone, iPad, or iPod touch - Apple Support
Take care.