I'll address the sex thing first, that could be because you have 2 under 2. I have 2 under 2 aswell and it's freaking exhausting because they're nowhere near as self reliant as my older kiddo. My partner stopped trying as I 9/10 said no and he doesn't believe in whining or getting upset to gain it. I go to him when I'm in the mood. If I'm not I'll tell him to watch porn and bash one out. He knows I love him regardless and I know he loves me but he understands I'm exhausted from the 2 womb demons and cleaning, cooking and all the other little things I do throughout the day (planning to open own business so research etc). Try and make her feel attractive and loved, treat her to a spa day or a trip to the hair and nail salon. 

Now for the cleaning thing it's all about training your mind to clean as you go, I used to be a once a week cleaner and then I became a chef and in our kitchen it was clean as you go, so I got used to putting dirty pots in the dishwasher, wiping down the sides before preparing the next dish, swapping knives etc. I find that if I have some music on (something with a good beat) keeps me motivated and in clean mode, once you've cleaned one area look at it and think about how your wife has it looking when she's done, is it the same? No? Then try and get it close as you can. In all honesty she shouldn't be starting to resent you because it's not to her standards she should realise that your putting in the effort to make her life easier and appreciate it.