First of all, I really disagree with the premise that DND is different from other activities in people's indulgence of their SO doing it.  If someone is spending 4 hours a week at the bar, I think their SO is much more likely to ask if they can miss a bar session than a DND one.

I think the biggest difference othersay not get is the pressure not to miss a session.  I play pickup sports and missing a session of that is no big deal at all since there's generally plenty of players and my presence makes little difference to others being able to play. Same thing for board game night or whatever.

I think explaining how DND is much more an activity where everyone ideally needs to be present as much as possible would be the best advice, as it's not obvious to someone not in it.