there's so much that can be discussed but i think its beyond an online forum.
i've seen a well educated, top ranking government official wife who is always abused by her husband, but she never chose to divorce him.
when i checked horoscopes, i found strong past life link where both these souls cannot leave each other in this life.
they tried past life regression to find that they were husband and wife (sex interchanged) in past life, where husband (present wife) abused wife (present husband daily) and now she's getting paid back.
until karma gets totally repaid back, they wont seperate and its a lifetime process, so only death of one person can stop this.
similarly, to experience collective karma, a group of souls (usually soul families) take birth in same family or as close relatives or close friends or business partners etc.
we can notice all of them suffering and going through tough time together.
soul families can be like owners of microsoft and intel, who could not make it big at same time if their hardware and software were not made around same time to support each other.
people with lesser karmic targets are born in same family.
it can also be known through a person's horoscope - his would be spouse, kids ruling planets etc