I can’t give you advice on next steps, but as someone who’s been in a fair few relationships, don’t be afraid to look around, ring young means you have time to explore and figure out what you it really want. No need to tie yourself down. If you find someone you click with, then by all means that’s amazing, but you’re under no obligation to find your life partner and invest.
Which takes me onto my next point. that feeling, where you don’t feel the same about them anymore. It’s completely normal, happens with the majority of people i meet, either one of us. you meet, you think you’re both perfect for each other, then after a few weeks, that lovestruck phase starts to fade away and you notice things that you just didn’t see before, because you were so blinded by your emotions. There’s nothing wrong with that, it’s perfectly normal, and out of your control.