I am raising two kids and although some days I feel completely alone I have a partner. All joking aside, Mike is great with the kids. I have been fighting the impulse to take over with them since...well always, but especially since Riley was born. I knew in my head I couldn't possibly do it alone, but my heart/hormones kept screaming that only I could do it "right." It took work to back off.
I imagine it's hard for any mother, but when you stay home with the kids it is your job. You spend 8-12hrs a day on weekdays (and some weekend days) taking care of the kids. It's hard to stop sometimes. During the week your partner comes home drained and doesn't, as my fantasies dictate, walk in the door, thank me and take over the kids. He's off the clock, but I'm not. After dinner, I calculate which nights are worth asking him to put the kids to bed and which night's it's just faster to do it myself. I save them up like get out of jail free cards.
Often when I have a break I find myself habitually tidying instead of doing something I need to do for me. I have to wake up out of my Mommy trance and tell myself to sit down and ignore that task for a minute. It isn't easy. In fact sometimes it's so hard to remember how to do things for myself I just don't for days. There is no physical boundary between work time and break time. This is one reason I find from time to time that I have forgotten to share the kid duties very equally.
Every now and then it'll occur to me Mike has no idea how to get both kids ready to go somewhere without me or Riley hasn't had a bed time story from Daddy in a while. It's important to me that my kids know they can get anything they need from either of their parents. It's also important to our relationship and my sanity that Mike and I always do our best to function as a team. Teamwork is not accomplished without a lot of effort and forethought. It is never, even on the best day equal (that's never the goal).
It's just a question of strengths and weaknesses. If it's crucial the kids go to sleep on time or the next day’s events will be ruined then it's my turn. If my ankles/back/hips/whatevers are swollen and I'm exhausted it has to be his turn. Mike is the go to parent for running around and fixing broken toys. You get the picture. You can't ask the other parent to do it your way (with any degree of success) you just have to make sure you're comfortable with them doing it their way before you ask for help.
If you are never willing to ask, I suggest you start learning to let go. I hope you find a loving attempt to back you up when you need it and your kids have a much closer relationship with both of you as a result. Just like with everything else there are good days and bad days.