Right now I'm theorizing it was a combination of both in that my journal entries are unusually void of the metaphors I usually use when referencing my emotional states.
I was taking it at the time we broke up, yes.
I was taking 150 mg extended release.
I agree with the above poster. This sounds unusual and it very well could be your medication. You were taking the medication during the break up, right? Either that's what caused the memory loss or it could have been too much for you to handle at the time. Or both. Do talk to your Dr about this and give him the time lines so he can decide if it was your medication or not.
(rxlist.com) "Tell your doctor right away if you have any serious side effects, including: fast/pounding/irregular heartbeat, mental/mood changes (such as anxiety, agitation, confusion, unusual behavior/thinking, memory loss), unusual weight loss or gain."
So yes, memory loss is a recognized side effect (I'd suspect more likely at higher dosages). What dosage were you on?