i have been thinking recently as i recently had to look after my friends little girl so her and her DP could go away for the night. both sets of parents don't babysit, they like to see the little girl but not actually ever look after her! and they just never have any time as a couple unless they go out seperately.
i would go mad without the support i have from my parents and DP's parents TBH. probably a lot of people on here will judge us for this but me and DP are always out without the kids! we have 2 kids aged 10 months and 3. since the youngest has been born last may, we have been away five times (for weekends away) and go out at night in town at least once a month, while the kids stay out overnight. and this weekend my eldest is going to my parents and my youngest is going to DP's mums for the weekend. and later in the year they are going to my parents for a week and me and DP are going abroad just the 2 of us.
also i am "lucky" in a way as my eldest is from a previous relationship so his dad usually has him 2 weekends a month, so there's a built in, unpaid babysitter! and when DS is at my ex's its easier and less stress with just DD so we get quality time then anyway.
i love my kids and wanted them very much but both myself and DP think it is absolutely essential for a healthy relationship to have space from the kids. I am a SAHM so am with them 24/7 other than when they are with our parents or DS at his dads.
but i honestly would not cope if we either didnt have anyone to help out or people were not willing. and i dont know how people can maintain decent relationships when they never have any quality time.