My sister is currently in the process of divorcing her husband. Together they have a preschool age son. They've had issues for awhile now I guess she wants out. The husband doesn't want the divorce. He insists their problems began after the son's birth and that the 10 years they were together before that were good. He says her previous PPD has caused both of them to behave poorly but that that's an issue that can fixed since they were happy previously. Sister denies she ever had PPD and says she's always been miserable with husband and therefore their problems can't be fixed.

The thing is, my sister did have PPD for I would say 2-2.5 years after the birth. We all saw it. She was diagnosed as having it by a therapist. She admitted it to various friends and family. Her own texts and emails to me show that she believed she had it. And though her husband definitely has issues of his own, I wouldn't say I noticed any major red flag problems between them before their son came along. Just typical relationship stuff. I'm not a big fan of her husband, but on this point he seems right. I haven't said anything to her about it because I don't want to get involved in their divorce or have her think I'm siding against her.

My sister's PPD thankfully subsided about 2 1/2 years ago, but before that we were all so worried about her. Now I'm worried that she seems to legitimately believe it never happened. Is that something I should be worried about? Is that common for people who suffered PPD?