Tbf that's totally different, it's just a tiny bit, it's like saying that if you like ketchup you also should like tomatoes, it's not the same

As a person that generally dislikes onions, it's different - I'm not a fan of onion flavor and don't like the texture, but I know it can positively contribute to a dish for me, primarily if it's not overly prominent.

It's like seasoning, eating some seasoning alone might make it taste bad, you might dislike dishes that use it as a main flavor, but if it's just a small component of a dish it might be a good thing. I haven't had marmite, but from what I've seen it seems kinda like that, very strong offputting flavor that complements other things very well.

Are you married to my wife? Are we a throuple now?

For me it's primarily the texture. I do like the flavor of onion as long as it's not overpowering. Cooked or not, biting into onion is like nails on a chalkboard but on my teeth. If it's chopped up small enough or powdered I don't have a problem. When my wife makes food with bigger pieces of onion, she makes them big enough that I can pick out.

For a long time, though, I would just say I don't like onion and try to avoid it altogether.