From a prompt by placeofold on Tumblr: Immortal Felicity (fluffy, angsty, take your pick).
It's better this way.
Oliver has been through enough in his short life without the prospect of finally deciding to be with her only to find out he'll grow old and die while she watches, forever young, impossible to kill.
She knows she could ease his mind with one simple confession, tell him that staying away from her for her protection is pointless because she doesn't have to fear death in the first place. But she refrains nonetheless. Not because she doesn't trust him to keep her secret—she knows very well he's capable of that.
Felicity has had many lovers in her years on earth, but none so damaged or frightened as Oliver Queen and she can't help but think that perhaps he deserves a less complicated love. Normalcy might be healthier..
So, she'll wait and watch because it isn't as if she doesn't have the time. She won't interfere as he tries to figure out what he wants and then if he arrives back at her, they'll go from there. She hopes he does.