"For the rest of my life, please wash my pants"
That's not even a joke that can be considered a legit proposal. My coworkers who got married shared their stories and one example was when he told her,"Until I die, please share my meals with me."
I think Morcheeba was referring to this: http://www.mangago.zone/read-manga/sweet_chapel/mh/c001/29/ (●'◡'●)ﾉ
Ah yes! I remember this manga. Could have had a more original confession, but he's really not far from the mark.
I'm just putting it out there that Japanese proposals are actually not straightforward. So the written note at the end of the chapter which asked the caretaker to continue cooking for him for the rest of his life, it's actually a proposal. This is just a bit of info for the readers who may be glossing over this little detail.