Background: Me and NDN have both been on a bit of a gardening vibe this year. We've been to the garden centre together and regularly chat plants. We have a running joke about us desperately trying to keep our plants alive because we're both novices.
Extra background (related): Her husband is a bit of a dick. He's not violent or abusive but selfish, lazy and a sulky man-child. I can give a list of examples if needed but won't clog the OP 
Here's the situation: She's going away for a couple of weeks soon when it's meant to be very hot and sunny. She said she's concerned about her plants dying because she doesn't know whether her husband will bother to water them.
So was I BU: I didn't offer to water them because it's not like the plants are home alone. I figured it's her husband's house/garden/plants so his responsibility. Even if he has no interest in the plants, he should at least take 10 minutes to water them for his wife, right?
But now I feel bad because I think she genuinely is worried about all her gardening efforts going to waste. It'd only be a case of me flopping the hosepipe over the wall and dousing them so no real hassle for me.
But then I flip back to thinking why the fuck should I, her lazy man-child of a husband should do it.