How to share workload better - any ideas?

[Stressymadre]

A bit of background first...
I live with my partner and my 2 kids (15 and 11), He is not their dad but very involved. My kids see their dad one night a week and EOW but my eldest is actually here most of that time and only goes to his dad's to sleep.
My partner and I both work FT, me from home nearly all the time but in a very highly pressured senior role, he runs his own business, so again, very stressful and he often works long hours.
A typical day for me: I wake at 6.15/6.30, wake the kids at 7 and I start work then. During my working day (on my lunch break) I will do some light chores (washing, dishwasher, online food order, life admin (!)) and sometimes walk the dog). I finish work at about 4.30/5 and then it is straight into kids' activities (they have on every night except fridays), walking dog if not done on lunch and sorting dinner.
My partner gets up at around 7.30/8 and is not back from work usually before 7. So he arrives home usually as I am cooking dinner and all chores are done.
At weekends we try to share chores and he does a lot of the cooking (I still do meal planning as he says I know what kids like better).
But, it just doesn't feel balanced and I think I might be being unreasonable! I know I have kids and he doesn't, so I have to factor that in, but I feel where I start work so early (my choice to fit around kids' activities) and I WFH, I am doing the vast majority of everything, despite working FT like him.
I suppose my gripe is that my life is just as busy as before we lived together, whereas he now has it easy as he gets home form work to a nice quiet evening!
So... firstly am I being unreasonable? Do I just need to accept this is life with 2 kids and FT work? And, what I can I do maybe to balance things out a bit more?

Have you spoken to him about this and if so, does he accept how you feel? Can the kids father do some of the after school activities ?

I have yes and he fully gets it and says he doesn't like that it isn't balanced. But where he works out of the house all week, I do't know how to make it any better! He would probably be happy to do everything at weekends but I wouldn't be comfortable with sitting around whilst he does all the chores, plus if I help, we get more time actually together!

From my own experience, do the kids need to be doing activities for 4 week day nights? They are getting to the age of perhaps wanting to have time to chill :)

(I still do meal planning as he says I know what kids like better).

This strikes me as the place to look. Why do you do it better? Because you are more practiced at it.

List out all the chores and household admin tasks, then divide and conquer. Make one person own each job. They then need to be fully responsible and accountable for that job. The other person should never have to think about it again. Also, while you're dividing up the chores, assign some to the kids. 11 & 15 is plenty old enough to have jobs that they are responsible for.

Thanks everyone. I like the list of chores - I love a list! The kids do do a lot of activities but they are both musical (eldest doing GCSE music) so between them they have activities every day (they don't each do things every day) but they have music lessons and orchestra practice, as well as doing a sport each.
The kids do help around the house but it is ad-hoc so I think the list will help.
As for meal planning, yes this is a good point - maybe another list of known meals we can go to to make it easier.

I should have been explicit but I intended to make the “learned helplessness” point more widely than just meal planning.
Writing out the list should help you find places where this applies.