
When I was 21, I was banging a 32 year old cop. The real deal, uniform, handcuffs, the lot. Whilst her 4 year old boy was sleeping in the next room. She was fine too, and very open minded. It only lasted a few months and I'm yet to achieve such a feat again
Tell you what though, as a 21 year old in that situation, you have the biggest balls in the town.
Loads of people are in bad positions because of poor choices - but your post seemed to be less "each partner could have contributed to the relationship breaking down" and more about how it's the woman's' fault for not realising that the father was a bit of a nob.
The only single mother I know was someone I worked with when I was 17, who went to uni, moved onto a very decent job, got married, had a child a couple of years later, and then the marriage broke down a couple of years after that because the guy thought that being faithful wasn't really for him. She is literally the polar opposite of the single mum stereotype.