And... It's a flashback.
We have Young Elly taking 6-year-old Mike and his active friends onto the monster movie matinee for his birthday. Is she happy about it? Heck, no! Children are a noisy, smelly, dirty, ungrateful burden so she's upset and doesn't mind telling the cashier that. Out loud. In front of Mike. No wonder he has issues.
In her crabbed-up mind, if she hadn't been forced to endure the unnatural horror of childbirth, she'd be young-looking and thin. Of course, she's full of crap. Her default negativity, pea-brained sloth and horrific diet would have stolen her looks if she were single.