If you were actually in their social circles, you'd know they sleep around, are sometimes intolerable, are high maintenance, needy, entitled etc. From the outside looking in, all you see is window dressing and women acting brand new. I once knew a pretty woman who would always flirt with a guy's friend just to make him jealous and get his attention. And then she'd end up with the friend, get pump and dumped, then finally pursue the original guy - only to get pump and dumped again because she rubbed his ego the wrong way by sleeping with his friend. She would do this over and over and over again. Throughout the entire social circle. To save her life, she could never directly flirt with a guy she liked. Her default mode was always to make him jealous.
And this is like 90% of pretty women. A lot of them can't get out of their own way. If you were in their social circles, the reasons why they are single would be 100% obvious to you. As clear as day and night.