my wife and i do talk about our relationship with my parents, but my wife is very determined that she doesn't want any more than we have now.
i could do as you suggest, and decide to take the children round to my parents, and leave them for the night, but how do you think that might play out with my wife?
yes - i absolutely talk to my mum about other things (the last time we talked about our situation was probably about a year ago, and prior to that, probably at least 6 months. it's not a regular conversation).
i don't even think my wife would claim that anyone is placing unfair obligations on her!
my conversations with my mum were never of the "mum, why does DW do this? why can't DW be like this?" sort. i've never used my mum to just have a bitch about my wife. that would be totally inappropriate.
and any problems my wife and i have had, we have always talked through with each other first, to try and resolve.
but if i've been unhappy, and my mum notices (as mums do), i'm not going to lie to her, or keep her completely in the dark. i don't think it's healthy to do that anyway!
i'm 100% certain my wife has done the same with her parents about me on occasion!
i think everybody should be able to talk about their relationships with key friends/family - provided they are balanced and objective, and aren't pushing their own agendas - which sounds like it is happening with you.