To answer the original question: Yes, I suspect it would make me at least somewhat paranoid.
But, I think it depends on what actually happened. If she was already clearly unhappy with the previous relationship; it would be a lot less likely to cause paranoia than if the previous relationship were happy. In the latter case, I think paranoia is quite likely.
And along with the happiness of the previous relationship, how it ends is also a factor. Assuming an unhappy previous relationship, if the previous relationship didn't end first, that's more reason to be paranoid (and also a more morally questionable situation, as already mentioned by others). I'm assuming that the new relationship at least started quite soon after the previous one. I don't personally think that's the best way to start a relationship, since it could have some sense of "rebound relationship". But, if Elta is pretty sure that she's a lot happier now than in the previous relationship, and if the transition wasn't too questionable, I could see paranoia not being required - even though I have no idea whether Elta would truly win a Most Charming contest.
All hypothetical, though.