OLIVER QUEEN
Ray Palmer:
To quote Felicity Smoak; "Barry Allen in Oliver Queen's body". You can see why he was jealous when you two met
BARRY ALLEN
Oliver Queen:
Though he and your father bumped heads a lot, he was extremely nice to you, understanding kids are not their parents. Barry got a little jealous when he realized you two had more in common than you and him did.
LEONARD SNART
Mick Rory:
They may have been partners, but that didn't mean they didn't argue. Mick flirted with you occasionally, but mostly for fun or when he was absolutely drunk. He was afraid you liked fire more than ice.
RAY PALMER
Clark Kent:
When you first met THE Superman, you may have gotten a little... fangirly. Then again all of the ladies did, he even got Sara to blush. Ray got a tad jealous before realizing he and Clark looked alike...
WINN SCHOTT
James Olsen:
Even though he is your sister's ex, you had a friendship with him that often gotten you two mistaken for a couple. On days when people assumed you and James were a thing, he became a little... clingy. Though you knew he would eventually realize it was stupid and move in.
JAMES OLSEN
No one:
You don't really have a lot of guy friends, so he never really needed to get jealous unless it was a co-worker that unknowingly flirted with you. Though he is a little jealous about the time you spend with Kara.
SLADE WILSON
Oliver Queen:
You had known Oliver for a long time, and though he had told everyone numerous times you were like a sister to him, it did seem you two had some attraction for one another. Slade doesn't usually show his jealousness, but you know its there
MALCOLM MERLYN (I meant it when I said it was going to get weird...)
Tommy Merlyn:
Yep, he was jealous of his own son. Tommy was closer to you in age, and Malcolm always thought you two were more attracted to one another. So much so, he didn't really have Tommy around when you were around. He would eventually get over this thankfully...
TOMMY MERLYN
Oliver Queen:
Oliver had been just as helpful as Laurel and Tommy during your pregnancy, he even bought you a beautiful bassinet from France. You were the only Lance to be excited when he returned from Lian Yu. And there is speculation that Diana considered him the better uncle, though you shot that down when you told Tommy he was her favourite and only step-dad
CLARK KENT
Barry Allen:
You had been close to him during the invasion, but that's because you like to say you owe him your life. Pre-flashpoint, you were dead at the hands of Damien Darhk, so when it was announced that one of the things that changed when he changed the timeline was your death, you couldn't help but thank him.
RIP HUNTER
Savitar/Future Flash:
Not Barry, but Savitar. It was revealed that in the timeline Savitar came from, you had been his wife and goddess, you had died at the hands of Vandal Savage and Savitar vowed to ensure you never died. He somehow gave Barry the idea to get you to join the legends to defeat Vandal and never die, he planned on taking you back once he reached ascension. He even visited the waverider to ensure you were okay.
ROY HARPER
Jay Garrick/Hunter Zolomon:
During his time as Jay Garrick on earth 1, he had managed to flirt with both you and Caitlin, knowing it would piss Roy off. It was later revealed your earth-2 counterpart was one of his trusted generals and was supposedly married to him