If you had to describe the relationship between Sethe and Paul D in one word, I think it would be safe to call it complicated. No relationship is perfect, but not every day do find out that your significant other has murdered their child. It’s hard to argue that either party in the relationship was mentally healthy enough to engage in a committed relationship. Both Sethe and Paul D carry extreme emotional baggage that often seeps into their present lives. This is not to say that they both don’t deserve a loving and committed relationship, but maybe they owe it to themselves to find another individual with a healthier outlook on life. I think that Solomon Burke sums it up perfectly in his classic You’re Good for Me. In this 1963 release, Burke sings about a complicated relationship with a woman he loves, but is constantly let down by. Burke begins with the melancholy lyrics, 

"You're a bad little girl, it's true/ But I'm not gonna walk out on you/They say you're a good for nothing, girl/But I'll stand up and tell the world."

When Paul D was informed that Sethe had murdered her youngest child, he fled the 124 household. Sethe’s moral image had become tainted. The lyrics depict Burke standing up for his mistress despite the fact that he’d already been informed about her toxic attributes. Though Paul D initially flees the house and falls into a drunken haze, he returns later, months after Beloved disappears. In addition, Paul D was originally hesitant to even admit that Sethe could have possibly committed the heinous act of murdering her own child.

Burke later laments,

"You're no good for yourself/You're no good for nobody else"

Not only did the decline of Sethe’s mental health take a toll on both Paul D and Denver, but her obsession over pleasing Beloved additionally caused her own physical appearance to decline. As Beloved became larger and uglier, Sethe seemed to wither away. Her physical strength and natural beauty began to fade.

 In the following lines, Burke changes his tone again.

"But you're good for me/Oh, you're good for me/Oh, sugar dumpling, can't you see/You're good for me"

Similar to how Burke seems to be trapped in a cycle of manipulative behavior, Paul D was once trapped between Beloved’s vendetta for her mother. As Paul D carries a heavy load of emotional baggage, he becomes an easy target in the crossfire.  

Burke finishes his tribute with the lines,

"That's all I'm living for/'Cause you're good"

After Paul D settled down in the Ohio home, his life began to reform around creating a stable home life. Though this would seem like an inherently positive change in his primarily independent life, it created an unprecedented interdependence between himself and Sethe. This subtextual dependence ultimately causes Paul D to return to the estate. For Paul D, there can never be too much water under the bridge.