How do I tell him I’m no longer going?

I was supposed to go home this afternoon to help my mom with my sisters bridal shower invites. My mom brought everything to me yesterday and today I used my Cricut to cut everything out.

My S/O offered to drop me off(I’m without a car currently). I spoke to my mom who said she’ll just come get it and she doesn’t need my help but that I can come home Saturday.

When I originally told my S/O I was going home he goes “oh ok, so you’ll be home for the weekend” I explained I was just going for the day.

I know me telling him I’m not going home anymore, he’ll question why even if I tell him my mom said she doesn’t need my help. If I say I’m going home Saturday he’ll probably tell me I can go home for the weekend.