Bye Bye Love

Bye Bye Love is a side quest in Fallout: New Vegas.

Detailed walkthrough
NOTE: There is no way to get this quest without passing at least a 50 Speech check or a 50 Medicine check.

The quest can be triggered by speaking to Joana or Carlitos, who reside in the Gomorrah casino and hotel (in the courtyard) and the Vault 21 hotel (in the mess hall), respectively. To activate the quest with Joana, pass a Medicine (50) or Speech (75) check to initiate dialogue that will eventually have Joana talk about Cachino and Carlitos. She will offer 200 caps or sexual services for taking the quest (the second option is only available if the player character is male, or a female with the Cherchez La Femme perk). If one can't meet either check, they can talk to Carlitos, who only needs a Speech (50) to find out about why he left the Omertas and Joana. Carlitos will give the player character 200 caps upon accepting the offer to help him and another 200 upon completion.

The first part of the quest involves ferrying messages between Carlitos and Joana. After some running back and forth, the Courier can agree to help Joana and two of her fellow prostitutes escape to Freeside to join Carlitos; the agreement being to wait until between 12AM and dawn, Gomorrah's busiest hours, before attempting the escape. Carlitos advises the Courier to get some backup before attempting the escape, as Carlitos knows two guns-for-hire that owe him a favor. This gives the Courier the option to recruit Big Beard and Little Beard, who are located in the Atomic Wrangler casino. Once the Courier is ready, they need only speak to Joana, who will then change outfits and walk to the casino floor where the other two prostitutes are waiting. Talking to Joana once she arrives causes all three to run to the meeting point in Freeside, which is down the first side street outside the Strip gate.

Once the player character meets up with the hired guns and Carlitos, four Omerta thugs will ambush the group. Go either go into combat with them, or talk them into leaving with one of three checks; Strength (8, 9), Speech (75, 85) or Barter (85 with 500 or 75 with 1000 caps). Carlitos and Joana must survive the confrontation or else the quest will fail. If successful, Carlitos will thank the Courier and ask if there is a way to repay the kindness. From here, there is a choice between receiving 200 caps or accepting a simple "thank you" for good karma. Alternatively, if the Courier talked to Carlitos first and they have a high enough Barter skill (65), they can get another 400 caps on top of the 200 at the start.

From here Joana will thank the Courier and mention a sinister plot she's heard about from Cachino about the Omertas. The How Little We Know quest will initiate if it hasn't already been activated.

Behind the scenes
The name of the quest is either a reference to The Everly Brothers' song Bye Bye Love or The Cars' song Bye Bye Love.

Bugs

 * When the Omerta thugs appear and turn hostile, they remain friendly to the player character and only attack Carlitos and the Beard brothers if present. This is because their dialogue script adds them to the Omerta faction after choosing a dialogue option that turns them hostile, instead of initiating combat.
 * Carlitos and Joana won't appear in the game if the Courier has advanced far enough in the quest How Little We Know, even after starting conversation with both, making the quest impossible to complete.
 * To fix this on PC, use the following console commands: For Carlitos:, ,  while standing in the same area of Vault 21 where he normally resides. For Joana: , ,  while standing in the Gomorrah courtyard.
 * The downside of this method is that once the Courier has escorted her and the disguised hookers out of Gomorrah, they may not move. A solution to this is to start combat with Joana, leave Gomorrah, then go back in and restart dialogue with her. After that, exit Gomorrah, enter Freeside, and Joana and the disguised hookers should appear, resuming the quest.
 * So far there isn't a way to fix this on consoles, as there are no console commands, except by reloading another previous save, but the bug might repeat.
 * After running back and forth a few times, the dialogue option to get Joana to run away might fail to appear. A high enough speech skill may be required in order to convince her.
 * When leading Joana and the disguised hookers outside the gate to Freeside, the securitrons posted outside the gate can become hostile, attacking all included people. Killing them gives infamy for the strip but letting them kill Joana fails the quest.
 * When Joana and the disguised hookers are waiting in the Gomorrah lobby the game can crash when exiting the strip, avoid this by allowing all four of them to leave first.
 * After escorting Joana and the disguised hookers to Freeside; Carlitos might not appear making the quest un-completable when Joana, the disguised hookers, and the Omerta thugs stand around and do nothing. Killing the Omerta thugs won't work since Joana, and the disguised hookers, still need Carlitos to appear to advance the quest dialogue. Reloading the auto-save from entering Freeside can fix this.
 * Once the group reaches Freeside, the thugs that are supposed to interrupt the escape, sometimes won't appear. This can be bypassed by using the console command "setstage 00110a65 90" and talking first to Carlitos once (before or after the command), then to Joana.
 * If the player character fast travels to The Strip North Gate once leaving the Gomorrah Casino, as opposed to actually escorting Joana and the disguised hookers, one or both of the hookers can glitch into the gate itself. This does not actually affect the quest as it's completed if Joana alone survives.
 * When escorting Joana and the disguised hookers past the Securitrons on the Freeside end of the gate to and from the strip, the game may suddenly crash, leading to a black screen before being booted to the Playstation Home screen as if one had quit the game.

Прощай, любовь Bye Bye Love