I have a pattern of occasionally forming extremely intense and extremely close friendships with people only to very suddenly go off them for literally no reason. 
Usually this happens with people with similar relationship behaviours to me, so the relationship escalates extremely quickly with very poor boundaries, to the extent that we almost merge. 
I’ve tried to stop doing this by constructing proper boundaries from the start and this does work, and most of my friendships now are very healthy. 
However, last summer I met a friend with whom I didn’t do this. Things felt very easy to begin with - we have a lot in common and things got very intense very quickly. We started texting everyday, all day, wishing each other good morning and good night. We told each other EVERYTHING - they helped me a lot with my mental health and I helped them. It felt well balanced and symbiotic. However - at some point things started to change. I had fallen into a pattern of literally sharing everything with them - but things started to feel intrusive. I became anxious I wouldn’t be able to maintain that level of intimacy, but I was scared I’d hurt them if I withdrew. So I continued to share everything about my life with them hoping the feeling would go away. 
But then suddenly  it became too late. I snapped. They had asked me something very personal, as we shared everything, this was normal for us, but I felt intruded and violated and repulsed. It wasn’t their fault at all - this is what we did from the start. But suddenly contact with them filled me with rage and everything about them disgusted me. 
I didn’t tell them this is how I felt. I know it’s not their fault. I still hoped the feeling would go away - so I decided to try to get some space. I knew I was seeing them in a group this weekend- so I asked if I could have space from texting for a week. I hoped if we had some space the love and warmth I used to feel would come back and the repulsion would go away. 
But it didn’t. I literally felt I couldn’t be near them. They walked up to me at some point but I couldn’t do it and was scared I would snap - so I made an excuse and walked up to someone else. 
This is breaking my heart- this person was so good to me and for months was my best friend. Now I can’t even talk to them. I don’t know why I am so suddenly repulsed. It was literally for no reason. They don’t deserve this and I don’t know how to tell them. 
Does anyone else struggle with this?