Keeping calm with my husband

Really trying to keep calm with him as we are TTC but he is irritating me. He is never on board with adjusting our budget to save for family vacations, but now he is dead set on crunching the numbers so he can buy a big boy toy and we are a one income family. I stay at home with our little one and go to school so I manage our money. He is impulsive and frivolous and now when we are TTC to finish our family, he thinks we need another monthly payment for something that he will use by himself. Anytime I disagree with him he gets defensive and moody and I know he will hold a grudge. Everything has been perfect between us besides this, it’s just that when he gets something in his head he can’t let it go. I just needed to vent but if you have suggestions I’d love to hear them!