I should just leave her to it shouldn't I?

[kansasmum]

My dd is married to a lovely guy and they have a ds ( who obviously I adore!).
For those of you who have grown up children how do you find the right thing to say when your dd/ds comes and rant at you about their partner?
My dd is very stubborn and compromise is not her favourite word!
She's been married for 18 months but sometimes she can quite frankly be really nasty to her Dh if they are arguing. He is very calm and doesn't rise to the bait so think this enrages her more!
She will rant to me and if I try offer a different perspective ( or subtly try and gently point out that maybe she needs to calm down!!) she will (not surprisingly!!) say I'm siding with her Dh!

If I say I'm not getting involved she says I'm not interested in her!
She is only 22 and r/ship is strong and I do not get in the middle of arguments and do tell her she has to sort these things out.
But how would you reply when she vents/ rants?
I am a people pleaser by nature so my auto response is to try and fix things. Obviously in this case it's their r/ship and I have to butt out and leave them to it! But id love to find the right words/ advice but perhaps there's not a right answer and I should just say it's up to you two to sort out!
Any help?

My mum just goes 'oh I see' and just appeases me. She let's me rant If having a moan about hubby and doesn't step in. Obviously if it was something serious she would speak her mind. What do you mean by being nasty to her hubby? How serious? Remember also he's a man and can stand up for himself. Ultimately if he's not happy with the way he is being treated then he needs to deal with it and speak to you DD. if it's just general moaning and for the sake of keeping relations with your daughter, I wouldn't comment and just let her vent. Try and subtly change the subject too if she's moaning for too long lol.