I've been on the receiving end of this & it wasn't very nice. I was suffering severe MH problems and struggling to leave my front door. My partner was working all the hours god sent to keep us afloat whilst I was ill. I cleaned within an inch of my life inside the house, but just couldn't make it outside at my worst.
Our neighbour (yes a retiree who cut their grass at least once a week) offered to do ours - we were initially grateful as we had no lawn mower and couldn't afford one, we got them a wee something as thank you.
However, from then on in this neighbour became an absolute nightmare with it. As I started to be able to venture outside, whenever I left my front door said neighbour would jump on me and offer to lend me their mower. It became very insistent even when I said 'we're busy today and have other things to do' - it just wouldn't stop there.
This then in turn became an offer for the number of a window cleaner etc.. our windows weren't horrid by any stretch, but definitely not pristine. Knocks on the door shouting at us to "cut our fucking grass" etc.
Now I'm better I work full time, overtime, lates, weekends and to be honest, whilst I appreciate some people really enjoy gardening and some find it a hobby, I have other hobbies, go the gym etc. I'm very busy and just don't have the time to worry incessantly about a garden - my interests are elsewhere. We do mow it, but we're certainly not out there cutting it weekly.
Your partner doesn't know their story - best to just keep out. Although we were initially grateful for what seemed an offer of help - we quickly realised it wasn't and was very much a hint - and if anyone offered us again I'm afraid due to past experience we'd very much take it as passive aggressive - perhaps unfairly. The amount of obsessing and fury this neighbour got from our garden made her seem unhinged - simply too much time on her hands and needed another hobby ontop of their garden. Best leaving well alone tbh.