Does sexual liberalism lead to rebirth in the hungry ghost realm? In DN 31, the Buddha said a libertine is an evil companion leading to ruin.


  There are, young householder, these six evil consequences in associating with evil companions, namely: any gambler, any libertine,
  any drunkard, any swindler, any cheat, any rowdy is his friend and
  companion.
  
  These are the six dangers inherent in bad companionship: any rogue, drunkard, addict, cheat, swindler, or thug becomes a friend and
  colleague.


In the Tanhavagga, the Buddha taught craving, particularly when developed, leads to woe and suffering:


  334. The craving of one given to heedless living grows like a creeper. Like the monkey seeking fruits in the forest, he leaps from
  life to life (tasting the fruit of his kamma).
  
  335. Whoever is overcome by this wretched and sticky craving, his sorrows grow like grass after the rains.
  
  342. Beset by craving, people run about like an entrapped hare. Held fast by mental fetters, they come to suffering again and again for a
  long time.


Therefore, if a person pursues and engages in sexual activity merely for sexual gratification, will they increase craving in both themselves and another? 

If a man, for example, has sex with a woman because his has lust but has not personal commitment towards the woman, will not craving be created in the woman leading her to keep searching for a sexual partner? 

Are those who are always searching for sex, love &amp; companionship destined for rebirth in the hungry ghost world or even hell?
Let me present the so-called Tathagata Dhamma viewpoint, represented by Dhammadhatu. The answer is no, sexual liberalism doesn't lead to rebirth in the hungry ghost realm. You may want to want to read this answer to see why, according to this viewpoint, rebirth cannot fall into the dhamma of the Buddha. If there is no rebirth, then, logically speaking, there is no rebirth in the hungry ghost realm either.