I think people really overblow Spinel's abandonment issues. The first time they flared up as a subconscious reaction to a painful memory she knew nothing about. Then she reasonably asked Steven "did you really only need me to stop killing the world" after she turned off her injector. And instead of just saying no and comforting her, Steven did literally the worst possible set of actions, first saying that yes he only needed her to turn off her injector, and then showed he still had the reset scythe and horribly told her that he wasn't going to reset her.
Like to me, she comes across more as a recently hurt person being more weary of being burned by a "friend" again. Like you just got burned after accidentally putting your hand on a stove, so you keep your distance from stoves for a bit until the burn is healed a bit. Only on a much grander scale because she literally experienced six thousand years of loneliness and suffering and then everything she ever knew coming crashing down on her TWICE in the same day. And she makes the reasonable assumption of "how the fuck can you like me? I tried to kill your planet, and you, and your friends!"
TL;DR: Spinel isn't your crazy EX. She's just really hurt.