I think he will. Especially since he was saying that he only cared about the 2 of them. He'll do it to try and save him and his boyfriend which will probably back-fire horribly.
"The saddest thing in life is wasted talent." ~ A Bronx Tale (1993)

Eric isn't really a team player, and he wants what is good only for himself and Aaron. He is going to be problematic.
They're gonna miss us when we're gone.

That's the vibe I got too. Eric's only been seen in a handful of scenes in the last season or two so for him to have an actual dramatic scene with real information in it seems to have doom (most likely his own) written all over it. Eric should have learned from Spencer's situation that Negan really doesn't respect snitches.

I felt that scene was to foreshadow Aarons's death.

Eric is Aaron's gay partner, OK?
Seriously, you missed that part?

When they first encountered Aaron in the barn (the episode where Rick punched him in the face) Eric was with him. Not right there, he was waiting in a nearby town. They hooked up with him at the end and traveled back to Alexandria together.

Are they family? I don't remember this Eric kid from before. Who is he? (I know who he was in this episode but don't think I remember seeing him in an earlier episode).

No way. Aaron's Achilles heel is his love for Eric. He would die himself in order to save Eric from harm.

How much you want to bet Aaron will be the one who has to kill him, to keep him from betraying the whole plan to the Saviors?

Good point. He probably will, otherwise what the hell was the point of that tiny scene he had with Aaron? They did that scene just to have Eric gain valuable info about the group.
The only other scenario is Rick's group won't return for days and Eric will be the one who will come forward and tell whomever where Rick and the rest ran off to.
Mother is the name for God on the lips & hearts of all children -Eric D. Raven