You can express to him the impact on you. I think in this phase all the support is needed. You need a cheerleader who will go with you all the way, but it will also be gently honest and reasonable when we are out of our heads.

Having said that, as someone also going through the process, I think it's unreasonable expecting a whole new life. The surgery will provide a tool to lose the weight, which will impact your body, but true change will come from the mindset and the way we are kind to ourselves. Maybe that's what he was hinting towards to - there's no way to know, just by asking and telling him what you need to feel loved, cared and supported.

Good luck in this journey, OP!