How can I leave a situationship?

There are many reasons that people can hang onto others in their lives off and on. Those reasons are different for everyone. Sometimes it can be due to arguments or disagreements that lead you both to not want to speak to each other. And then time passes and maybe you miss each other. Then you two may reach out and reconnect. But if you two don't discuss or work on the disagreeing factors, then these issues can come out over and over again. It sounds like you have awareness that it is toxic to be around this individual. What is it about this individual that draws you to them? What would it mean if you stopped communication with this person? Perhaps it's easier said than done, but something to reflect on from you end. 

Attachment styles can vary from person to person. Sometimes we may perceive that we are not loved if we stop communication with that person. When they return, we may interpret that as we are valuable and lovable. But having someone around doesn't necessarily imply that the person is invested or helping us grow as individuals. And sometimes people avoid intimacy or don't necessarily feel worthy of it. Thus, they may avoid it. And then others may feel as if they want it, but perhaps are not ready or know how to receive it. Unless we feel like we are worthy of love, it may be difficult to heal from an insecure attachment style. And working on finding value in ourselves can make all the difference in navigating how we feel and behave in any relationship.

Letting go of any type of relationship can be difficult for some people. As you mentioned, past attachment issues can lead one to try to hold onto a familiar relationship -even if it isn't the healthiest one. And breaking from what feels comfortable can be a bit of a struggle for some of us. Sometimes it can be due to our parents or caregivers and how they brought us up. Other times, it can be due to past traumatic experiences that have led us to feel a lack of trust with the people in our lives. Regardless of what the reason may be, it is important that we acknowledge that this is impacting us.  

Learning to break from a relationship that feels comfortable, but isn't the most healthy for us is a process. Sometimes it may actively mean slowly moving away from that person (or at our pace). It may feel uneasy to know that we won't be able to see or talk to this person anymore, but it doesn't mean that we can't reach out to others in our support system. This may mean that we may lean on them more than we usually do and that makes sense as it is a transition. It is also a time for us to refocus on ourselves and our goals. And reminding yourself that this process may be uncomfortable, but it doesn't mean that it isn't going to be best or helpful for you in the long run.

Learning to better understand attachment styles and where we come from can be something that we can self-explore through workbooks or self-help books. If we feel like we need additional support, we can always reach out and start individual counseling with a therapist or counselor for more support. Best of luck to you on your journey to heal.