Keeping Communication Strong
No matter how tired or frustrated you are, the biggest keys to coming through this period with your relationship strongly intact are communication and compassion. Don't stop talking to each other — that's how little things add up and turn into big trouble.
First of all, if you don't clear the air regularly, that annoying little thing he did last week (like forgetting to clean the diaper pail) can fester under the surface until it becomes a Very Big Deal in your mind. Also try approaching disagreements without attacking or being passive-aggressive. Saying “You never help around the house!” is more likely to cause a defensive reaction or a fight than the less accusatory “I feel frustrated when I've been up all night with the baby and see that the dinner dishes are still on the table.” Keep your complaints on point — don't bring up the time he blew off dinner with you so he could stay late at the office a year ago. It may feel relevant, but it won't help the current discussion about what needs to be fixed in your house right now. And more than one mother has complained that loud sighs, slamming doors, and stomping around the house doesn't do much to get her partner's attention, either. The key is directness without too much drama.
Keep in mind that both of you are probably on edge: tired, stressed, and anxious. Try to be forgiving of one another's snappy comebacks and sarcasm. If you approach each conversation assuming that the other person has good intentions, it's easier to avoid common communication traps and to keep resentment from taking hold.