I hate lateness. I was raised by a type A father, and for a while I was very “who cares” about timeliness, but once I got out in the working world I realized that people who are late often make other people late. I changed my ways around age 17 and have seen no reason to change them in the past 26 years.
For the past 13 year I have been a nurse, and it is considered “professional courtesy” to be early. Actually, my nursing school teachers drummed into us that on time was late, because of the various duties needed at the end of/beginning of shift… count narcotics, give report, maybe do an assignment sheet, etc. I personally feel calmer if I am early to post, because I can start my work (and not the administrative hassles) at 0700h.
My co workers know that if I am not at work by 15 minutes to the hour they will be hearing from me. One day the bus made me late, (5 minutes to!) after that I changed routes and began being 25 minutes early, because I don’t like starting a shift worrying and hurrying.
Of course I have co workers who are consistently late and after mentioning it a few times I gave up. My boss does alternate mornings that she starts at 7 (and arrives at 645) with mornings she starts at 8 so she is aware. I wish she also came in and saw what happens at 11 pm, with me there at 1035 and the other nurse breezing through report and leaving at 1050. (Yes this is the same one who habitually arrives at the building at 702, goes upstairs to sign in, arrives to my floor at 706, chats then if I am lucky hand off and count is done by 716. I detest the staying late for him, but I arrive early mainly for myself, so I am not about to give that up.
All that says nothing to car pooling. Your situation would make me crazy. You have to let him know you finally mean it. I don’t know if he will get it, unless you actually leave without him.
Does he know your marital situation? Can you tell him “Look, I like arriving at work early so I can get home to my kids early. Things aren’t easy at home and I really need to be there for them. Please respect that.”
Then stick to your plan, leave without him, if he isn’t on time.