Mahakali88 was a good example of this.
She seemed to be getting her life on track, job, friends, got a new place, ordered new furniture, etc - then in the space of a few days had a few setbacks and emotionally challenging problems and ctb with SN.
I think it didn't help she had some underlying issues with the fairness of the world, and wrongly belived this evil place had taken one of the people she admired most from here - who promptly re-appeared after she'd gone (she'd been trying to contact him/her to no avail) and they acted kind of oblivious to it all.
Hadn't even commented on her memorial or her thread where she was going to go.
Anyway, I think once the thoughts are there, it doesn't take much to re-awaken them.