<human>: Could you distill the essence of the text into 1-3 sentences?

My SO (unmarried, longtime committed) and I have been together for 12 years. Everything was great, almost daily sex, lots of leisure time, we supported each other until we had kids four years in (surprise! Twins!). Things went to hell in a handbasket, lots of acting out and neglect on the part of him. He wouldn't even "babysit" his children, the filth collected in our house until I dealt with it. He changed jobs, quit due to a bad fit, and then remained unemployed for a full year. 

Fast forward to today and he's the cleaningest, cookingest mofo you've ever seen. He gets the girls off to school, does homework. He accompanies his daughters to ballet class and is very encouraging and active in their lives (which I love). Dinner is on the table when I come home. I am still the breadwinner but he works a flexible part time job in his field and so most of the household duties he takes on himself. I am so, so bad at these things myself so when I was in charge of them they got done but in a lackluster and no-extra-effort fashion. I should be grateful.  

Recently he's requested that I put down my phone, get off pinterest or reddit or whatever and be present. I remember begging him to put down the video games when our girls were born and how much it hurt that he wouldn't. My phone is still glued to me. We sometimes watch movies together at night, I always fall asleep before the end and he gets upset so I don't even want to do that anymore. He wants me to want him sexually and I just don't. 

Why do I long for an imagined new person to be wanted by when presumably they would not fit my family's needs anywhere near like he does… and this new man would want sex and attention the same as my current partner? Why don't I feel like I can give it to him though he is fulfilling my needs? What do I do?
<bot>: My SO has a lot of great qualities and when other women I know complain about their partners, I have nothing to say. I don't understand why I don't "want" him and how to start wanting him again.