Well, when you're talking about their relationship "in the beginning" that's when Cordelia is using Alys as her local guide to Barrayaran high society, and they're both pregnant (the pregnancies progressing normally) and married with living husbands. That's the point when it's valid to consider whether they would have stayed each other's closest confidants if there hadn't been the Vordarian pretendership. But if no Vordarian pretendership, Padma lives.

But because of Vordarian, Padma dies and the two women are flung together in the closest of possible circumstances -- Cordelia and her team rescue Alys and Ivan when Padma has failed to do so. So the "what might have been" if they had grown apart after the initial coincidence of circumstance that threw them together has disspated never happens, because the bond of shared danger, comrades in arms and so forth brings them so close together any differences are largely superficial.