Husband gives up when baby cries

So little baby is having a lot more false starts and is a bit more difficult to put down at night. Four month sleep regression is starting, I’m assuming. I’m trying to figure out what I can adjust in her schedule or literally anything to make it easier but as we all know babies sometimes don’t work that way. My husband has been taking care of getting the baby down at night so that I can get at least a few hours of sleep before she starts waking throughout the night - she’s up at least twice. But now that it’s more difficult he gives up and says I have to do it or we let her cry it out which is unacceptable to me. I feel like he only agreed to doing bedtime when it was easy and I feel so betrayed that he won’t do the difficult parts too. I’ve been getting her down for reluctant naps all day and the one time I get a break…. I think he owes me a huge apology but he’s weirdly stubborn about this - and he literally was never like that before having this baby. I don’t know what to do.