I gained nearly 100 pounds while living with my ex. Why? At first, I'd say we were enablers for each other. I didn't care that he was overweight, and he didn't care that I was overweight. We ate out a lot together, went shopping at the grocery store together, and indulged together. It was fun at first, but got old when I realized what was happening to my body!

I still tried to occasionally eat healthy as I had in the past, but he would quickly put a stop to it, telling me he loved me the way I was, that my weight didn't matter, and that he felt rejected when we didn't eat the same things together. He'd get way bent out of shape if opted for a veggies or a salad, and of course it was ten times worse if I merely suggested that he try to drink less soda (he easily went through a 12 pack or more a day) or that maybe we should have less fast food (which eventually became a daily habit).
One day I'd decided I'd had enough, and that he wasn't going to have any control over what I chose to put in my mouth. It was an uphill battle.

It involved more than hurting his feelings, he'd actually scream at me when I nicely asked him to stop bringing home bags of fast food on the way home from work. He'd call me a stuck-up b*tch if I ordered a salad when we went out. He'd buy my favorite treats and literally stick them in my face, calling me a loser for caring about others thinking I was fat. It was often easier to give in to his demands rather than stand up for myself and endure a huge, unnecessary fight. Either way, I'd end up crying and miserable, and that's no way to live. It took me a while to realize that he "needed" me to join in as his little food buddy, otherwise he'd feel guilty for indulging whenever I was actually trying to eat healthier and take care of myself. And he'd try to pass his guilt to me. And when I really started putting my foot down, ate better, and started losing weight, things got even worse. After losing the first 40 pounds, he claimed he was no longer attracted to me because I had "let myself go." Er . . . let myself go? Just when I'd started caring about myself again? He was taking all my food decisions as a judgment call against his and that never really ended as long as we were together. We eventually (and thankfully) broke it off, and without his issues hanging over my head I had an easier time concentrating on what I needed to do for my health. I now weigh less than I did when I met him.
Not saying your case is as extreme or that you need to break things off with him like I did with my ex (there were more severe problems beyond just the food issues that are far too numerous to mention here), but maybe my story will get you thinking about the difference between his wants and your needs. You need to be healthier; the quality of your very life depends on it! It's not fair of him to coerce you into eating something you don't want to just because it "hurts his feelings." There has to be a compromise somewhere, and there has to more to spending quality time together than ordering fattening food. It's likely he's using you as his own enabler.
You've recognized that the weekly binge leads you nowhere with your progress, and it looks like it paves the way of keeping off-plan for most of the week. Pick a neutral time to sit down and talk with him about your concerns. Don't even focus on the weight, bring up the fact that you need to be healthier, that you want to have more energy, that you need to feel your very best in order to be happy. Explain that
he shouldn't take
your food decisions personally. Discuss potential options that will work for both of you. Could he order that pizza while you make yourself a fresh, home-made salad? You could feast on your salad (since you made it, you have full control over what goes into it and how many calories it is) and have maybe one or two slices of the pizza he ordered to go with it. He can even buy the salad ingredients if he still wants to be the one to treat. Or he could buy the ingredients to make a pizza and it's something you could do together at home (once again, allowing you full control over what goes into your portion). Ask him to be open to different restaurants where you can both find something you like; Olive Garden offers more than pasta, pizza, and breadsticks for example, they have some great soups that are low calorie. My husband and I occasionally go there and he'll order pizza while I get the minestrone or pasta e fagioli soup.
He and I often have pizza nights at home, but instead of ordering Pizza Hut like we used to, we'll buy a medium thin crust from the Walmart deli (serving sizes and calories are printed right on the box), and while it's baking I'll prepare my salad to go with it. It's cheaper and more fun than ordering in, and gives me more awareness of my portions and calories, making it less likely to indulge too much.
Ideally, when you're in a relationship you should be helping each other and taking care of each other's needs rather than conforming to selfish wants and enabling bad habits. Him guilting you into indulging certainly isn't healthy for either of you.