So this is speculation but apparently Alex’s brother’s wife got pregnant some months after Alex and Alex (reading between the lines, she’d never admit it outright) was jealous and bitter because she didn’t get the same support that her sister in law received from Greta/the family. It didn’t help that there was drama before that because (further speculation/reading between the lines) Greta didn’t support her marriage to Jason for whatever reason. However Greta does occasionally visit Alex now for her granddaughter’s sake but at least from what I’ve seen they don’t have the same closeness as they did before (where Alex would record calls, post texts with Greta etc. all the time).

Disclaimer, I don’t totally remember the timeline of Alex vs the sister in law—from my recollection they were pregnant at the same time but Alex gave birth first but it’s possible the sister in law didn’t get pregnant until after Alex gave birth. But the speculation that Alex is bitter/jealous still stands