This sounds a lot like someone who is already in a relationship
That sounds a bit harsh. As a guy I can tell you it can simply be due to long distance. If there is little perspective to see each other regularly it’s easy to lose interest, especially if it’s not your first relationship and you haven’t spent that much time together to begin with like in this case
Honestly I don’t think the UX is bad. Sure, a few things could be improved, but it’s in a great overall state, especially considering its current growth rate