deal breaker??

Me and my so have ben together for almost 7 years now.. we have a toddler together.. i ha e ben telling him for a while now i really want to try for another.. well last night we were talking about how my sister just got a puppy& he’s like i want a puppy& im like i want a baby.. and then proceeds to ask me why i would do that to our son.. because when his dad had another kid (his sister) he treated him badly& now theyre relationship is strained.. and now i just know i just deel soooooooooo defeated because i really want one more baby& now the fact that i feel like ill never get that from him im not sure i can spend the rest of my life with him. im not sure if thats petty, but I’m honestly so heartbroken..