Communication, communication, communication... It's all about being genuine. You're upset that you put some weight back on and have a harder time feeling pretty and desirable when you and your boyfriend are being intimate. I know what that feels like. Well, not the "pretty" part, but certainly the part about feeling a bit heavier than you'd like to be.
So, your boyfriend noticed that you put on some of the weight you worked so hard to get off. How did that make you feel? Did you tell HIM how it made you feel? Did you tell HIM that you're afraid he doesn't or won't desire you anymore? Did you share your thoughts and fears with HIM?

He may have just been making an observation about your weight gain and nothing more. ASK him what was going on in his head when he said that! TELL him what's going on in YOUR head.

I dunno... I know that what I'm saying here, the whole communication thing, sounds a lot easier than it might sometimes be, but nevertheless, that's the first thing a couple needs to do when EITHER person is uncomfortable or upset about something. TALK to each other and share what's on you mind or how you feel!!! Otherwise, you aren't a couple. You're just two individuals who happen to live together in the same house. Frankly, I think that talking and sharing thoughts and feelings is one of the sexiest things a couple can do... When you do that, you're telling your partner, "I Love you enought to be vulnerable with you".

Anyway... I don't want to carry on about it as much as I tend to do, but honestly, genuine communication with your partner forms the basis for a strong relationship with the person you Love.

And that's all I gotz to say about that.

Dan