I remember reading the other translation of this, and think that this one might be slightly better. That said, Eris's logic doesn't work for me, and think it's bad writing and poor characterization. She should've just tried to communicate with him, and she also could've gotten stronger beside him. Now she's just setting herself up for being ditched for the next charismatic girl Rudeus sees, and also traumatized him unnecessarily while setting off a journey that might not even bear fruit.
If she really loved him, she should've talked it over with him and cleared things up, and made a decision together with him. Real couples talk to together and make important decisions like that together with mutual love, attention, and respect. The fact that she took off like that thoughtlessly without any effort to consider how he'd feel and what the consequences might be shows that she doesn't love or understand him as much as she thinks she does, and that she's really not ready for a relationship and that someone else (ironically) might be better for Rudeus.
At any rate, I think this is the point where I feel like this series started going downhill, and I now much prefer the Roxy spinoff.