I have regular scheduled alone time each week. DD goes to FDC on Fridays (originally so I could do some casual teaching shifts) but I've been quite unwell so Fridays are mine and so are Saturday nights and I can have more time when I ask for it. DP has Wednesday nights to himself to go to his dance class and for dinner.
If I don't get this time I become narky and critical and not very nice to be around.