I know IABU for not minding my own business but this is really bugging me and I don't think it's fair. SIL and I get on quite well, she tells me a lot about her private life and I've always been there to listen and help as much as I can. About 2 months ago, she told me that her boyfriend has moved in with her so they can save money for a house deposit. She said she hasn't told UC because her payments would be affected as a result of how much he earns and they can't afford to not save the extra money. I told her that I'm sure she can get in trouble and get a fine if they find out and she said they're 'just seeing how things go and if it works out first'. I'm really annoyed about this because I feel like it's benefit fraud and she shouldn't be lying to them regardless of how much her payments will be affected but at the same time I also don't want her to get in trouble. What would you do?