Why are there soo many single mothers in America, who gives these men permission to walk out when they've had enough fun with a woman?

I lived in the U.S for two years when i was 5 years and i was brought back here (africa). When i was in America i saw neighbors were so suspicious of each other. One would complain if the other's dog crossed to their porch yet sometimes they greet each other (for formality i guess). Everyone minded their own business and if you had a problem you either find an inhouse family member to help because your problems can never be shared with neighbors or extended relatives. We'll over here i can cross a stranger's compound without any suspicion. From what i see right now, single motherhood is like a lifestyle in America and people treat it like its normal. What happened? Is it the culture of self-centeredness that has made men to take women's time, have kids then divorce them after fulfilling their needs. How comes women sacrifice to give men their time and have kids with them only for the men to walk out after a couple of kids. Women feed the ego of men and afterwards the men go for better deals elsewhere. Divorces happen everywhere in the world i know but its not normal if 3 out of 5 households are single mothers. This is what happens to a society that thinks humanity is leisure. I dont understand how kids grow up wounded by the mistakes of selfish parents. FIY, i wanted to vent, don post hate messages, just give your opinion if you feel like you want to contribute. I am not married so maybe i dont understand all that happens in a marriage. But im in a capable position to see whats wrong and give my opinion