The pair went their separate ways and called time on their relationship, but up until now, fans have never discovered why...
Now on a break for almost a month, the fifth season of 'Arrow' is gearing up to round off and tie up some loose ends, but not before two fan-favourite characters go head to head in an episode titled 'Dangerous Liasons'.
Stephen Amell as Oliver Queen aka Green Arrow in The CW series 'Arrow'
With the villainous Prometheus (Josh Segarra) still at large, both Oliver (Stephen Amell) and Felicity (Emily Bett Rickards) have their own ideas about how to take him down. Disagreeing on the best path of action to take however, one of the most tense showdowns in the series' history is set up as the pair take each other on.
Showrunner Marc Guggenheim has now revealed that those working on the series would be answering a lot of fan questions when the fifth season makes its return, especially when it comes to Oliver and Felicity.
Promising that they would "deal with the consequences" of Oliver and Felicity's romantic split, he added in a chat with TVLine: "They never really had a full-on discussion or exploration of why that breakup happened. Felicity just sort of reached her breaking point and walked out the door.
"It comes out of the events of 519 and, quite frankly, all the other episodes that led up to it. Something happens in 519 that really tees up this conversation."
Though we're not sure exactly where the clues are pertaining to the break-up, we do know that Oliver has in the past driven a wedge purposely into meaningful relationships simply to keep those he loves out of danger. We can't see that being the reason for his split with Felicity however, as she's a pinhead of Team Arrow and consistently in danger's way, whether romantically linked to Oliver or not.
Felicity is unafraid to get her hands dirty and seems to be more reckless than ever in recent episodes, being dragged further into the hacktivist group known as Helix. As they continue to consume her mind however, she faces being ostracised by the group that hold her so close. Could she turn it all around, or will the forces of darkness consume her forevermore?
'Arrow' returns Wednesday, April 26 on The CW in the US and comes to Sky1 in the UK soon after.