Elizabeth despairs of making James understand. Her Commodore cannot comprehend why she would break faith with him for one such as Sparrow. To spend her time with Will would make sense, her fondness for Turner having long preceded his piracy; James even sharing her fondness to some degree. He has commented that should Will ever wish to turn respectable again and avoid the gallows, he would gladly put in to get him a letter of marque.
But Sparrow… Jack Sparrow is unredeemable chaos, no orderly lines, no fine sense of honour, nothing at all to temper his illegal activities, to make him remotely acceptable to an English officer, and so she fears that James will never understand.
She loves James, of course, he truly is a fine man, a good husband. Undoubtedly he will be a fine father to the child that grows within her. And she is quite grateful to have married James and not Will, for all that Will is a fine man and dear to her heart, James is stability in a way that Will cannot be for her now. And that is what a home and children require, stability.
It is a quiet life, and a good one, that she leads, for James is not so boring as she might have feared and neither is being his wife. But for all that it is good, for all that at least the sea has not been stolen from her, she misses things she can no longer have. And so, she spends her time with Sparrow, and knows that her husband keeps a watchful eye on her. He is, at least, forgiving of this fault of hers, this fascination with pirates and chaos that lingers even now, even as her belly swells and the responsibilities that will come when the girl is born. (Somehow, she knows both that the child is James's and that the child will be female. She supposes it is no stranger than a medallion of cursed gold calling out to the men damned by it.)
Some days, she feels like asking him to come along to show him that it is not an attempt to escape her responsibilities for a day, but a way to remember what the salt air tasted like on a ship not bound by any government's orders or duty to anything but one's own self. It is a reminder of the trade that she has made—and that, perhaps, as wistful as she may be at times, it was not a bad trade. Sparrow has a way of infuriating her without even trying, usually on the topic of Will.
She dances around the subject of Will during her visits, for Will is an uncomfortable subject for her, and Sparrow usually ignores her evasions completely. He likes making people uncomfortable, even the ones he's about to sleep with. Perhaps, she thinks, especially those. It amuses whatever perverse demons that possess her soul and make him quite mad and daft. Will is, unfortunately, neither one thing nor the other, not quite a respectable blacksmith and not quite a dashing rogue, but Sparrow says he has finally begun to truly fight dirty and it only took an ugly scar on his cheek and nearly losing his eye to a dagger. Elizabeth is too aware that she has played a large part in shaping Will from the blacksmith she knew and respected and loved into, of all things, a pirate—a thing she also loved but that was not him; too aware of the unspoken promises she could not keep and the chasm that lies between them now.
Perhaps it would make sense to fall into Will's bed, to think of the man who got away, but Elizabeth has hardly ever done the sensible and obvious thing in her life, so it is Sparrow she kisses and Sparrow she fucks and James she loves and James she thinks of even as Sparrow is in her. She supposes in a fantasy world she would have them both in her bed, light and dark, order and chaos, a perfect balance.
She does not live in a fantasy world, as fantastic as her world has been. She lives in a world where compromises must be made, where duty and freedom barely hold an uneasy truce and one can not blithely slip from one to the other without a price to be paid. James is forgiving, but distrustful and worries at her, concerned for her and the child. Sparrow hardly cares at all, he has many beds he can sleep in aboard his ship and on land, and it is only that she is an intriguing mystery that she has him at all.
In another world altogether she might have spurned her engagement to James and none of this would be—in another world it would most likely be that she would share Sparrow's bed with her husband, Will Turner. But this is not another world. She argued for their lives, argued to let them free, but she stood with her husband-to-be and watched as the two men disappeared over the same ledge that she had tumbled from herself. Her heart is a complex device not so simply defined as one thing or another and it had ached to watch them go, but it would have ached just as painfully to stand with them, to carve such a wound into James's heart.
Perhaps James will understand, some day. Sparrow is not as different from him as might be. The sea is in their blood, at least, and to cut either off from it would just as surely kill them as a bullet between the eyes. Perhaps her fantasy world is not so impossible as it seems, not so impossible as the might-have-beens in that seem to follow her everywhere. Perhaps she will feel the scratch of Sparrow's dreads as he sucks at the hollow of her throat and James spreads her thighs, perhaps she will feel James's soft lips against her breast and rough hands on her hips while Sparrow sinks into her, perhaps she will whimper as two men bring her pleasure and she brings them.
Perhaps. But most likely not.
He is the Commodore, after all, and Sparrow is the Pirate.