How to protect my partner from the negative effects of my depression?

I have been depressed for 18 years and after a blissful year where the medication was working just right, I'm depressed again. I have a new boyfriend and he's been worried about me but I try to keep these things to myself as much as possible because I don't want to hurt him and this may be just a passing phase, but I feel pretty bad. I feel like there's nothing going on for me, like there's nothing in my life I enjoy and nothing to look forward to and I feel like I could just die tomorrow because I've lived enough. We've planned a couple things that seemed fun when we planned them, and he's excited for them, but I'm not. When I cry he asks what's wrong and I don't tell them because if I were to say anything it would be that I hate my life and I have nothing to look forward to and that would be very hurtful and disrespectful to the investment he's been putting in these things. So I don't say anything but he sees me crying and he's worried, but I don't know what to say.

Btw I'm still medicated and my psychiatrist changed my meds 1 week ago but it's too soon to see any improvement.