I honestly forgot about that meeting in the storage room, and I can't believe that was never brought up to Runa before until now. Glad that was used as a point to prove MC's feelings and devotion to her, and yeah, he had a point, if his past with Maria is that much of a problem for her, they should stop dating.
Don't know when Runa started saying 'the past doesn't matter' (when honestly it does for a lot of cases, but that's just me), but yeah, probably shouldn't be a hypocrite and try to follow her own advice. Hopefully this puts an end to the Maria-conflict arc.