It depends on the severity, I think. Obviously if your partner is abusive physically or otherwise then the best thing to do is speak to someone outside of the relationship that you trust to discuss that.
But I'm talking about your average bickering and fall outs.
The reason I ask is that I'm quite annoyed at my partner of 1 year. We have the odd spat every now and again. I found out this weekend that he'd told his sister about a fairly big disagreement we had a fortnight ago (subject of which is not v interesting and bears no reference to this). I think he may have told her more than just that but backtracked when he saw that I was put out about mentioning things to his DSis.
I do really like this guy and hope that we have a future together. I've only met his sister 2 times. (Don't live v near them and I have DC to look after mosr of the time). I've not had much of a chance to build a rapport with her. I know she likes me. But she adores her brother. If he talks about problems between us, I feel a bit undermined and unable to counter any negative feelings about me that she may start building about me. I'm not there to put my side across.
I've a feeling he's done the same with his mum (who I've never met) but he won't admit it. I overheard her on the phone to him while he was at mine. When he said he was at my house that weekend, she said, 'Oh good, you're ok again now then, are you?'
We're both in our 40s, each have our own DC, don't live together.
I don't want his family members judging me. I don't want them talking about me negatively behind my back. We're only just starting out and I want to make a good impression on his family. This doesn't help and feels, frankly, quite disloyal and counter productive.
I'm close to my own sister. I wouldn't dream of telling her about disagreements. I never involved her in anything like that during my 10 year marriage (ended a few years ago). (I told her all about the problems I'd had after I ended the marriage - a whole other thread.)
I just think that mud sticks in situations like this. Blood's thicker than water too. Discussing the minutiae of a relationship with family can do more harm than good. Dodgier than discussing with friends who wouldn't be so territorial about you. I wouldn't expect my own sister to take my DP's side about disagreements, so why would his sister take mine?
What do you think?