Technically they never married, which is why the original article uses a bunch of other phrases to describe their relationship, but agreed that the change from "partner" to "lover" makes the title needlessly provocative. "Partner" was fine.
Oxford actually has (as one of three definitions):
either member of a married couple or of an established unmarried couple. "she lived with her partner"
a person with whom one has sex; a lover. "make sure that you or your partner are using an effective method of contraception"
I see the same thing happening in Spanish - no one can say “novio/a” anymore. Why?
In light of all these facts, I, for one, would say that "partner" is an impoverished term to use in this headline, because what really does that signify? A business partner? Come on. There are obstacles here to clarity of terminology, due to the dubious nature of her legal marriage and such. But this is a woman who seems to have leveraged her sexuality to every advantage, as well as being taken advantage of in return. Not a good scene!
I've noticed a trend, especially in Commonwealth or European countries to use "partner" to mean "sexual partner" or "romantic partner". However, it's also used in business, sports and many other contexts. Just saying "partner" on its own is less clear than "lover".