Lama Ole’s answer:
Yes, it is quite possible that in a previous life someone took your partner away or killed you. This could be your karma.
This is actually one of the reasons it is so difficult to stop wars. Many beings kill each other and then meet again in another life in all kinds of countries just to kill each other again and again. The only antidote is that the people in an area become so positive that those with bad karma don’t get born in those countries anymore.