Elmira is the worst wife ever. She doesn't eat dinner with her family, preferring to sit in the loft with her legs dangling over the edge instead. She yells at her husband every day about buttermilk. (Cool it, lady, it's just buttermilk, right?) And she insults her husband in sneaky ways. For example, she says, "If you don't [go after Jake], I guess you'll be yellow the rest of your life" (27.21). She's talking about July's jaundice, a condition that turns his skin yellow, but you know she's also using it as a dig at her husband's bravery, or lack thereof.
She doesn't love her husband. She doesn't even love her son.
"If she didn't love her husband and her son, who did she love?" (28.4)
Well, she lusts after her baby daddy, Dee Boot, but we're not sure if she is capable of love in any way, shape, or form. Something has made Elmira hollow inside, and it's not the fact that she was a prostitute before she met July. Lorena was a prostitute, too, and she still has a heart.
Elmira abandons her family, boards a whiskey boat, and heads after Dee Boot. Her journey is tragic—in her mind—because the day after she reaches Dee, he is hanged, making her whole trip worthless. Along the way, she gives birth to July's baby and—surprise—abandons that baby, too. At least she leaves young Martin with Clara, a woman who will raise him much better than Elmira ever would.
Once Dee is dead, Elmira rides off on a suicide mission with Big Zwey, a whiskey trader, and they both get killed. Because Elmira pretty much considered her life over after losing Dee, we doubt she cared. No one else seems to care, either; in fact, we find out about Elmira's death after it happens, off the page.