What is the ruling regarding a wife who requested a divorce and was divorced by her husband, who then took her back two days later, and then another dispute occurred in which the husband said, "Rely upon Allah, and whoever is not content with her life, let her rely upon Allah and leave," with an unspecified intention?

A divorce by implication (kinayah) does not occur unless you intended to effect it. If you doubt your intention, the divorce has not occurred, because the original state is the continuation of the marriage. Divorce also does not occur by mere self-talk without uttering it. Based on this, your divorce has not occurred by any of what you mentioned. It is advised to be wary of obsessive whispers (waswasah).