Do you know for a fact that she is jealous - or are you just supposing that she is?

> I don't think she thought taking an object like that would destroy our relationship

Yeah, that wouldn't make much sense.

> but I did/do fear that it was just the beginning of her efforts to take out her frustration us.

So you think she is feeling frustrated with you both...

> we spent many fun times with them as a couple and grew to really like them. Even though they broke up, we let her know we would still enjoy seeing her sometimes and to not drift away.

Ah. It can be hard when you are friends with people in virtue of being part of a couple. Hard to know whether they would continue in their friendship when things break up, or whether their loyalties lye with the other half of the couple. Since you are so close to her ex it would be understandable if she were to feel like when she lost her ex she had lost you as well.

> If she's so frustrated and in need of a bond, why not take it out on someone she doesn't know so well?!

You seem to think that in stealing the item she did to to lash out at you. That her action was personally directed toward you and that the motives were frustration and anger.

I was suggesting that there might be another way to cast that. It could be that she took it for her own emotional needs (to have a memory of him perhaps) and the harm to you was more an unfortunate byproduct of her action than the intent behind her action.

Like how sometimes we need to get an immunisation or something and it hurts like hell. The doctor doesn't intend to hurt us like hell, however, the point of the immunisation isn't to hurt you - it is to help you. Even though it is forseeable that the act of delivering an immunisation will hurt the person. I'm not suggesting she was trying to help you in taking it. But I am suggesting that sometimes consequences of our actions are unintended by-products rather than the reason why we do them.