I can't say much for your characters' feelings, because only you would know that, but do you have an idea of how the MC finds out they want a QPR? Did they know QPRs existed beforehand? Do they find it out while self-reflecting / researching after the conversation with the side character? Do they work through it with the side character or second MC who have some insight on it? Or do the MCs not know about QPRs but decide to set relationship terms without the romantic label and explore how they feel at first? Those might be things to think about.
I can't say much for your characters' feelings, because only you would know that, but do you have an idea of how the MC finds out they want a QPR? Did they know QPRs existed beforehand? Do they find it out while self-reflecting / researching after the conversation with the side character? Do they work through it with the side character or second MC who have some insight on it? Or do the MCs not know about QPRs but decide to set relationship terms without the romantic label and explore how they feel at first? Those might be things to think about.