Every family (parents and siblings) needs to remember that your married son/ daughter (brother/ sister) cannot become available to/ for you, without the consent of their spouse.
And every spouse will freely offer that consent, if s/he has been embraced as a loved/ respected/ valued family member – in the first place.
The elders fail in their duty if this doesn’t happen in a family. Alas, most elders don’t pass this test. And families break up.
Though the blame usually falls on the shoulders of the “outsider”; the fact remains that as long as even one member remains an outsider (in energetic sense), the family in any case is not in its integrity. It is a family only in name.
On top of that hidden loyalties (things done on the sly) add fuel to the fire.