Basically the fiancee just said "I'm his fiancee, we are bethrotred from born because of his unreliable old man and I say this just to make you at ease"
100% sure MC doesn't think with his dick. Also his fiancee is fully focused on gaming. The 'fiancee' status is just a thing their parent decided as actually MC run from his house to marry his commoner wife
Nice but kinda want to cringe when i see game addiction, even though i can't really speak as i have a "reading WN" addiction.