I've never quite understood how the "Wants your provinces" modifier works, but here's how I think it works.
- The larger/stronger a country who wants your provinces is, the higher the negative modifier will be. A country far smaller than you, for example, could say they want a bunch of your provinces, but still have only a negative modifier of -10 or so. And then a country like France comes along, and gives you a modifier of -200 for the same amount of provinces.
- If the other country has a claim/core or something like a mission to colonize a specific province, it will result in a higher negative modifier. You'll notice this if you play in one of the colonial regions, and suddenly you have -200 "Wants your provinces" with Castille.
- "Wants your provinces" modifiers are not permanent, but seem to come and go over time. You might very well be able to regain the alliance with France if he changes his mind. I managed to do exactly that in my current game after he stopped wanting one of my provinces. The reason for this could have to do with ruler personalities. If the ruler changes and the new one has an administrative or diplomatic instead of a militaristic personality, that might make the modifier disappear.
Like I said, I'm not completely sure about this, so feel free to correct any of these points.