I own a small design firm. This would also bother me. If I were asked about this professionally after this work was done - and if the client didn't want to tear up the tile and get a larger countertop top and incur that cost and headache - here would be my two solutions. Neither are perfect, but they would no longer call so much attention to the issue. 1) Use the same countertop material - to fill over to the right and left. It would have a seam, but a good fabricator can do this. 2) use a wood transition piece - that looks exactly like the wood vanity (stained and cut to match) to overlay the gap from the vanity to the floor. You can call a finish carpenter to do this. If you don't want to do step 1, you could fill it completely with a wood transition piece. But the difference in the color would call attention to the lines - which I am guessing would continue to bother you.

Consider removing the door casing and the top row of tile on the end wall. Skim coat the wall plumb and tight to the counter. Reapply the tile end splash and door casing (using what was removed if salvageable or get replacement). Repaint. It's the only straight forward approach that will keep you happy and not bring up other issues.

You probably also have a gap at the top . I'd try to right size the fridge. By the time you horse around , the appearance will be far better if it fits. Or get the cabinet maker for all sides.........including above. Forty two inches means a taller fridge. Sound like the town house was designed with some luxury in mind. Another solution might be well made custom stainless panels made locally to fill the gaps. All three sides ( affixed to plywood as a "frame" around a 36 inch standard size stainless.) I assume/hope you will keep to the counter depth variety if that is what you have.............

I'll voice dissent. All my doors are 30" in this house, so the openings are less than that. It's not ideal, but it's better than my last house that had several 24" doors. If you've already lived with it, and it didn't bother you, I don't know why it would start to. Older houses have quirks. I'd rather have a pinch point than no counterspace on one side of the stove. (Had that at my last house too. Hated it.) (ETA: if changing the pantry situation might be in the budget later, better to have the base cabinet next to the stove now than to change both the pantry *and* the base cabinet later.)