My partner recently left me without giving me an explanation or reason. I feel so betrayed and helpless, how can I make them feel guilty for leaving me in such a manner?
user
Write them a letter detailing how their actions have made you feel and the impacts it has had on your life. Outline how their sudden departure has left you bewildered, drained and in anguish.
Outline the unfairness of their actions and remind them of your loyalty, love and support over the years.
Concisely summarise that all you are seeking is an explanation. End with the request for them to contact you to discuss this further.

Being straightforward, honest and heartfelt might help open up dialogue - which is all that you can hope for at this stage.
assistant
My partner recently left me without giving me an explanation or reason. I feel so betrayed and helpless, how can I make them feel guilty for leaving me in such a manner?
user
One way to make your partner feel guilty for leaving you without an explanation is to point out their lack of respect and communication. You could say something like, "You haven't shown me any respect by leaving without saying why. Communication is key in our relationship and I want to know why you decided to leave me." Additionally, you could also express your feelings of insecurity and loneliness as a result of their actions. That might elicit guilt and lead them to open up about their reasons for leaving.
assistant
My partner recently left me without giving me an explanation or reason. I feel so betrayed and helpless, how can I make them feel guilty for leaving me in such a manner?