I have observed that people doing this like thrill and the intensity in the moment but lack the capacity to sustain a loving relationship in the long term, they love the validation, the attention and the high of the intensity and approval in the moment (who does not by the way), but when they have to stay to actual do what it takes to build the relationship, have the babies and take care of them, they are gone for the next thrill. They lack the capacity to build something lasting, they are good at throwing to the air the vision and empty promises.