I don't think that's the case, I may be wrong because theres a lot of avriables and flags etc, plus I havn't gone through Ridley's route myself, hell I havn't even completed the game either. But from when I was translating it, I remember coming across dialogue regarding this. No matter whether you're on NTR route or not, I believe she always loses her virginity to Ed, well, aside from the early boss defeat scenes, but since they lead to game over, can't really count them. The stuff she had done with Gael before the point you're at was stuff that didn't involve penetration. I believe it's the same on the Antera route too, or just before the branching point, she still has sex with Ed, even knowing that he might not love her back, she still gave her virginity to the guy she loved.