If you’re the child of a single parent and you aren’t in the upper class, you’re probably a “latchkey kid.” That is, you spend a lot of your after-school time unsupervised while your parent is working.
You learn to cook, take care of your things, and otherwise fend for yourself. Years of that independence causes you to grow used to having alone time.
I’ll often feel guilty when my girlfriend helps me with something, because I’m so used to taking care of so many things myself — even though she loves me and is more than happy to lend a hand.
I can’t help it, and I imagine it stems from how guilty I’d feel if my mom came home from working her second job and I’d only created more work for her in the meantime while she was doing her best to provide for us.
So don’t take it personally if you’re dating a child of a single parent. This is just standard-issue emotional baggage that comes with the territory.