LOST's island was nothing near Fantasy Island for romance and healthy, healing relationships.
In fact, the time on the island for romance was crude, rude, manipulative and disastrous.
For example, Ben's dog bone was in perpetual heat throughout the series. He was so creepy that women around him did not need their instinctive creepy meter. When he could not hook up with Juliet, he killed her boyfriend. That must happen a lot to psychopathic losers.
Even when Juliet found a partner, he was killed or in the case of Sawyer, manipulative for survival mode after the time skip. It is hard to tell whether Sawyer was attracted to Juliet in the Other's camp, or merely using her to game the system. But in the end, most people think when Juliet died after the Swan implosion, Sawyer was hurt and emotionally scarred by the loss. He started to blame others for the death. He reverted back to his old, con-man self.
Kate was the master love con artist. She manipulated boys throughout her life, leading one to rob a bank just to get back a toy airplane. She hooked up with Sawyer not out of love but as a means of trying to get the weapon to neutralize his advantage in the castaway camp. It seemed that Kate was destined to be lost in love. Her relationship with Jack was doomed from the start. She spent her entire life running away from responsibility and accountability while Jack had the opposite drive as being the miracle surgeon.
One of the most tortured love lines was with Sayid. He claimed, pined and did horrible things in order for him to re-connect with the love of his life, Nadia. But despite those personal vows, he had a quick affair with Shannon before she was killed. How Shannon eliminated the years that Sayid lived for Nadia was illogical.
It was also illogical for Hurley to "find" Libby on the island. She was clearly in the mental institution day room prior to the plane crash. Was Libby there to stalk an innocent, fragile nerd like Hurley - - - for his wealth? The time line is unclear, but it seems Libby was there prior to learning of Hurley's lottery winnings, but after her husband died. It was clear Libby was recruited to come to the island to manipulate the castaways in taking a side during the island control battle. But it still seems that Hurley had more of a connection with the store clerk he lost to his best friend than with island Libby. When Libby died, Hurley mourned but he seemed not have grown by the experience to want to live a normal life.
Locke never had a normal life because he self-sabotaged it. He has a caring, loving relationship with Helen, but Locke ruined it by his deep bitterness toward his parents. When Cooper stole his kidney, Locke's fragile psyche led Helen to demand he cut off contact. But he did not, causing Cooper to push Locke out a window which lead to his paralysis. Even after that one devastating incident, Helen could still care for him - - - but Locke ruined it by going back to his father to try to find answers.
Charlie got the answer he did not expect from Claire when she rejected him (during the time Locke was being helpful toward her new born, Aaron.) Charlie was always in search for a deep family connection, but he was left drifting after his brother got married. He had a one sided crush on Claire, which was crushed by rejection. This led to Charlie believing his life had meaning so he "sacrificed" himself in the dumbest way at the underwater station.
The one pre-existing couple, Sun and Jin, actually broke up during their island stay. There marriage was doomed from the start. She was the neglected daughter of a rich industrialist. He was a dirt poor son of a fisherman. He dreamed of being a wealthy man. Her dream was to be accepted as an equal by her father. When she could not attain that, she tried to sabotage her father's reputation by marrying a common loser. But when Jin suddenly turned into a lackey for money, Sun was once again neglected - - - this time by her husband. Their story line ended in a muddled accident-suicide in the flooded submarine (Jin made the decision to give up his life and die with Sun instead of trying to live to raise their child.)
Did anyone find love and happiness from their island experience? The answer was clearly no.