Tips on cleaning more:
Pick up as you go. For example if you have popcorn and are finish with it take the bowl and put it in the dishwasher. If you have a laundry sorter sort your clothes as you take them off. Go through the mail immediately instead of piling it up for later.

Clean without being asked or told. This is my absolute biggest pet peeve and it does lead me to resent my partner at times.  I suspect that this is really the root of the issue with your wife but I can’t be positive. What I mean by this is that you are a grown man and you know what a clean house looks like. If you see that the floors are a little gross sweep them or vacuum. Do not wait for your wife to tell you to do this. Do not wait for a list of chores to do from her. This is mentally exhausting and already she’s doing half the chore by just realizing it needs to be done then seeking you out to tell you it needs to be done. By this point she’s thinking if she just did it herself the chore would already be done so she does it herself. 

Look online for a chore list and check it off each day. Eventually this will become habit and you won’t need the list anymore.

I can’t say for sure if this will help your sex life but if you start putting forth effort without being told or asked to do things, you just do them on your own everyday your wife will be less burdened and will see you in a more optimistic way. Which should have a positive effect on your sex life. I’m willing to bet she feels just as much as your mother as she does her 2 kids. Picking up after children all day sucks she probably feels like she’s picking up after you all day too and she’s grown resentful