how old is your child?
i have found that hubby and i DO argue more. i think most of our serious arguements involve the children and discipline or his mother's "approach" to our kids.
i think that part of the problem is that we have so much more pressure on us know compared to when we were just the two of us.
finances:
when it was just the two of us, if money was tight, then we'd just have noodles/dumplings 3-4 times per week. we didn't go out, we downloaded stuff on the computer to watch etc.
once kids come along, you can no long cut back in the same places that you once did. it isn't healthy for the kids to eat instant noodles 3-4 times per week etc. then when the start school, you have the added expenses of that etc.
sex:
before kids, we seemed to have a lot more energy... now, not so much...good cuddles, if we don't fall asleep first, if we are lucky most nights.
time off work:
before kids, you could do what YOU wanted to do.
after kids, you do what THEY want/can do.