You were asking. "whats wrong with me?"
Nothing is wrong with you. Seeing the PHOTOS brought up a lot of emotions you had probably already forgotten about. Psychology calls it a conditioned response. It can happen tyo anyone. What I suggest is not to focus on this, You've had your trip down memory lane,thats enough. dont dwell on it. Leave it alone now and direct your attention to something more pressing.
This is important you need to analyze whether you have been unhappy for a while now, or is it just this "incident" that actually triggered you to think you are unhappy. this might make and break the future of the relationship you are in so you really need to know where your heart stands concerning the matter.;)