Was I right to offer this?

So my boyfriend of 5 months recently started working construction, he works 12 hours a day, 6 days a week. He’s also house sitting for a family friend. He ALSO works his grandparents farm and his family’s land, not a farm, but similar, as well as well as other house work besides clean.

As far as I know his 14 year old sister does nothing, which I find unfair.

He told me he felt crazy overwhelmed and didn’t know how he’d do it all, so I told him to give me a call if he wanted me to help at his new house to clean or anything else, and he thanked me profusely, I never grew up on a farm but I grew up working my family’s land too, so I’m no stranger to hard work, I’m 21, he’s 20.

I told my mom, as of now I’m not working and work way less than him anyway, and she flipped. She thinks that it was out of like and I shouldn’t do that for him, that his family should.

His family won’t though, and I’m not gonna let him get anxiety over stuff I could help with. He only has one day off and if I can clean house and cook him a nice meal once a week I will.

He lives 40 mins away, but it’s a small price to pay to make him happy.

EDIT:

His sister is very spoiled and treated, well, like a girl. He’s worked both pieces of land since 10-12. I think it’s time for her to do something but until then I at least wanna help around his new place or mow his folks lawn.