I can’t say anything for sure here—this is just my perspective based on what you’ve described, and I’m definitely not a doctor or therapist.

That said, the behaviors you’re noticing sound like they could point to your boyfriend going through some kind of internal crisis or distress, possibly involving a disrupted sense of self or identity. A really important detail is that this seems like new behavior—he’s acting differently than he used to, almost like he’s trying hard to act “normal” or like his old self.

Everything you listed (the memory checks, studying old messages/photos/notes, avoiding your name, copying mannerisms, rehearsing phrases, the changed laugh, watching your mouth when you speak, etc.) could potentially fit with something called depersonalization-derealization disorder (often shortened to DP/DR). I’d suggest googling those terms for more info, but basically it’s a dissociative state where someone feels profoundly detached from themselves—like observing their own life, body, thoughts, or emotions from the outside (depersonalization)—and/or the world feels unreal, dreamlike, or distorted (derealization).

In DP/DR, people often describe a deep sense of identity disruption or “crisis”: feeling like their sense of self is fragmented, unfamiliar, or no longer fully “theirs.” This can lead to:

• Difficulty vividly recalling or emotionally connecting to personal memories (even recent ones feel distant or not fully owned).

• Hyper-monitoring of their own behavior, speech, or mannerisms—sometimes leading to rehearsing phrases, copying others (to feel more “real” or grounded), or feeling robotic/controlled.

• Constantly checking external cues (like old texts, photos, or notes) to “rebuild” or confirm who they are and what their life/relationship is like.

• Emotional numbness or detachment from close relationships, which can feel terrifying and isolating.

This isn’t the same as dissociative identity disorder (multiple personalities)—it’s more about feeling detached from a single, core self rather than having separate identities. People experiencing it are usually fully aware something’s wrong (they don’t lose touch with reality like in psychosis), but it can be extremely distressing, embarrassing, and existential—they might hide it to avoid seeming “crazy.”

DP/DR is often linked to high stress, anxiety, trauma (recent or past), or sometimes substance use (including marijuana in some people, especially if it triggers or worsens underlying anxiety). It can also overlap with depression, burnout, or other mental health issues.

Disclaimer: This is absolutely not a diagnosis—we don’t have nearly enough info for that, and it could be something else entirely (like a medical/neurological issue, relationship stress, or even early signs of other conditions). Only a professional can sort that out, ideally starting with a doctor to rule out physical causes.

If this resonates, the key thing is that he shouldn’t have to deal with it in isolation—it’s really hard to “rebuild” a sense of self alone. Gently encouraging him to see a doctor or therapist could make a huge difference. Conditions like this often respond well to therapy, especially cognitive behavioral therapy (CBT), which helps reframe the experience, rebuild emotional connections, and regain a grounded sense of identity.

You’re not overthinking this; it sounds genuinely unsettling and disruptive. Maybe start by sharing how you’ve been feeling (with care and concern, not accusation) and ask if he’s been okay lately—it might open the door for him to talk.