Yes, they definitely go through these phases. I remember one right around when my daughter was 2. What we did which worked really well was to get her involved in cooking. So she helps me made dinner almost every night. This made it a bit more fun for her and it also helped her to try new things that she then realised she liked.
I also have since about 18 months or so made a real point of making only family meals that we all sit down and eat together. She doesn't get a special kids meal or food I make specially for her (with some exceptions, like if we're going out for a date night meal later, then we don't eat with her). But I make one meal for the family and we all eat the same thing. If she doesn't like it or want it, that's fine. I don't make a big deal out of it, but I don't make her something special and she doesn't get anything else just because she's still hungry because she didn't eat anything for dinner (usually she has an apple or grapes a yogurt or something for dessert, but only if she eats dinner).
We also make it a point to eat everything in front of her. You mentioned that your partner only likes certain things. Could it be he's picking it up from him? If they see you avoiding certain foods, they'll be more likely to avoid them too. But if they see you eating and enjoying everything, they're more likely to try it and maybe like it as well. It might be a case of forcing yourselves to eat things you might not normally to get him interested in trying new things.
But yes, it really is a phase and they go through lots of these. The best thing you can do is just to keep offering lots of variety and not limit what you offer because you think he won't eat it. If you keep offering it, one day he'll happily eat it again. It just takes some time.