I find this so offensive. YABU.
The worst part is when your child has an accident late at night and you don't own a car... because you rely on state benefits and can't afford it. So you get two buses at 11pm to a town 40 minutes away because that's the only place there is a pediatric ward. To be sent home past midnight with no buses or trains, to walk to the town overs train station just to find it empty. Then to beg the caretaker to phone you a taxi you can't afford, to beg your parents to lend you the money for a taxi because you need to cover food until you get paid again.
To not have anyone to share those moments with that you would share with a partner, to share them on Facebook instead and have people mock you for being a "baby bore".
When you are incapacitated with flu or sickness bug and your baby is crying and needs to be picked up and there is nothing you can do but try and sleep on the floor of a safe space so you can rest in-between trying to care for your moving baby.
When your baby is really ill with a temperature and are worryingly irritable and you are up all night, no one to help, no one to put the kettle on or talk about what to do, to rationalise what is actually happening.
When you get stressed more than you would like to because your whole world is this all encompassing responsibility that no one else can take on, that no one else has a share in (unless an active father). And your friends talk about looking forward to the weekend because they get a break, and all you can think is that you can't see any break in your future.
To juggle even the time to bathe around keeping your house at a suitable level of cleanliness with a small child who doesn't sleep more than 2 hours at a time while also caring for your own personal hygiene.
No - having some alone time is not the same as being a single parent. It is understandable that one might feel this sometimes if not thinking about the realities but it is not rational and it is offensive.
But being a single parent is better than being in an unhappy and potentially abusive relationship.