I have seen the idea that girls who say they are looking for relationship are actually looking for a casual fling, and those who are looking for a casual fling are actually looking for a serious relationship perpetuated often in TRP/PUA circles. Can anyone shed light on the TRP justification behind this assertion? I'm having trouble understanding it at face value.

EDIT: I suppose I mostly mean why do women post these sentiments in public capacities, like on social media, in front of large groups, or on dating services like Tinder or Bumble.