If you and the woman are just trying to have sex then you should not be meeting her kids.
A suave, zen-like guy who can hold in his inner lion is great but if you have a temper tantrum throwing lunatic around your baby, you need to drop him like a bad habit.
The child is already dealing with not having a mother and father married to each other and living together, and needs parental attention.
That child does not need to compete with you, and you don’t need to compete with that child.
It is not your place to discipline an unruly child either, check his/her mom on that, and if it gets too much – call it a day and leave.
Having to play daddy when you’re simply dating a woman is not fair to you either, so don’t ever let them lay that on you as a responsibility.
Women you gotta be smarter than this, go back to his place, keep your kids out of it, and leave the little ones with a babysitter.