I can't stop blaming myself for my neighbour's broken marriage

I live together with my friend in a compound with two other tenants, Landlord doesn't live with us. One of the tenants whose apartment is adjacent ours is our close friend, a young man of 28 years who is married with a daughter of two years and a very young pretty wife of about 21 years.

Two weeks ago, at around 11pm, I was watching an action movie with my friend when we started hearing noises from our neighbour , the one who is our friend. They were arguing in these lines "I will get out of your house and never come back again....I am tired of this marriage...F**k you....F**k you too...You motherf**ker" 

Then I told my friend to lets go intervene and help them settle whatever they might be arguing about, but my friend said "No, it's their business, lets increase the volume of the TV so we won't hear their arguments again...let husband and wife settle their differences themselves" I obliged reluctantly, and since it was an action movie we were watching, with the sporadic shooting and sound effects, we couldn't hear them again.

Fast forward to the next morning. The man was dressed and ready to go to work at around 8am, then he entered our apartment and said , "Guys, don't tell me you didn't hear I and my wife argue yesternight" My friend retorted sharply and denied, "Nope, you know the Generator was on and we were watching the TV so loud" Then he broke the bad news that he lost his temper and beat his wife mercilessly because she spent the money he kept with her for the building of their house, so the wife parked all her belongings with their daughter at around 12am, got into a taxi and swore never to return to the house again and he told her "So be it" Then he said, "Perhaps, if you guys had shown up, I wouldn't lose my temper, my wife wouldn't pack her things" He then vowed never to accept her again. I tried to persuade him but he remained adamant.

I called the wife same day and she said she was currently in her parent's house, and she thought we purposely didn't want to intervene, then she said we were wicked. The wife and her family said their daughter would never return to the man, and the husband and his family said they also don't want her again for squandering their son's 400k, for not being savvy and for being promiscuous  (Her promiscuity I know of) . She seems too young to be in marriage hence the youthful exuberance.  They got married because she got pregnant.

I have been feeling guilty ever since. If I had just gotten out to intervene, if I just didn't listen to my friend,  their marriage would still be intact because I am highly respected by the couple;  they would listen to me had I talked to them. The couple have helped us a lot. The husband had come to our rescue on many occasions as regards money, the wife cooked for us like she was our sister. I had an opportunity to restore their marriage and I failed. How do I get over this feeling of guilt? And the funny thing is, my friend doesn't feel anything, he doesn't even miss the woman and their daughter unlike me, he doesn't even like bringing the issue up. He is just too unemotional.