For example, relationships regularly ending with sudden trauma, with person never knowing the friend's/partner's/etc real attitude towards them (i.e if they are actually loved), where said trauma is impossible to process ever or processing takes forever because of large delay in emotionally responding, never feeling satisfied or properly attached and fully trusting to really open up, with zero positive subjective (internal) experience of the relationships, relationships consisting of person being constantly emotionally manipulated into attentiveness, performing the resulting obligations without getting much back, people leeching off person's vitality and energy and emotions in the relationships, and so on.
These are just some examples I thought of to try to make up what the worst possible relationships would look like You can add more and you can give your reasoning for which type has the worst relationships and why. Note I'm not asking about the type that's the worst at relationships. But you can add that too