In my opinion, it's only a matter of time for something like this to happen, and it's heavily hinted at in both the opening (lyrics and Miorine shedding a tear) and ending.
Suletta has a gentle personality because she was raised and pampered by a sweet mother, which is exactly what Miorine never had. Suletta expresses her emotions freely, while all Miorine knows how to express in public are anger and indignation. One could even argue the opposite, that Miorine is such an emotionally stunted tsundere that she doesn't know how to properly comfort others, and it would be sorta canon too, as she just yelled at Suletta while she cried. I'm not saying this is a bad thing, since I'm sure both have a lot to learn from each other.