My sister in law is in her early 40's and single as she has been most of her adult life. She is attractive and has lots of friends but has never had a relationship work out long term. I do generally feel she is fine being single although she was very upset when her last boyfriend broke up with her.
The issue is that she does end up getting overly invested in other peoples relationships especially that of her siblings. It is obvious she has opinions about how other people do things and she often can't seem to help herself in saying what she thinks even at a family gathering in front of other people. Stuff that is really none of her business in regards to how her brothers and their wives raise their kids, split household chores or their financial arrangements.
She made some comment to about my and her brothers financial arrangements at a family dinner last week and I had to bite my tongue not to say something like "if you could hold on to a relationship for more than 5 minutes maybe you wouldn't have so much time to worry about what other couples do". Obviously I would never say that, it would be a horrible thing to say but it does really annoy men. I can see her sharing her opinion in a private conversation where you were talking to her about something but to just pipe up with her judgements about your marriage unasked in pretty unacceptable in my opinion. She does it to her other brothers and their wives as well and even if she has a point its literally none of her business.
I don't really know how to deal with it, I've tried talking to her in the past but she says she is just a tell it like it is person. I do think she is overly invested in her siblings marriages and families because that is something she wants for herself and she is often at a loose end and dropping in which is fine but she doesn't know when to back off or not stick her oar in. I am actually fairly laid back but one of my sister in laws is a lot more reactive and there have been several fallings out over this.
I am being unreasonable to think my single sister in law should butt out of other peoples relationships?