Sounds like you guys are in a classic "Mars vs. Venus" relationship. You feel the need to vent and use him as a sounding board. He views this as useless whining and would rather you focus on solving the problem instead of complaining.
I'd say the key is compromise. Vent to a girlfriend or your mother instead, unless it directly involves him or your child. Talk more about the positives with him, because the negatives will go in one ear and out the other.
It will be tough to find the right mix, but it can be done. Good luck!