Ready for Baby #2 but SO is not...

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How do I get my SO on board with another baby. My DD will be 3 this month and she keeps asking to be a big sister. I keep talking to my hubby about it. He always seems on board but when it comes to actually following through he doesn't want to. I'm getting a bit depressed about it. I will be 35 in May and I feel my time is limited. I don't want my daughter to be alone.