Have you ever met someone and got along famously, only to have them back off suddenly? Perhaps you reacted by ignoring them when they finally tried to get in touch a few weeks later, and now, ages later, are still wondering what happened.
There is a good chance that you simply became involved with a person who suffers from fear of intimacy.
Seen as a social or anxiety disorder, fear of intimacy often results in a person blowing hot then cold, or doing the occasional disappearing act, which can be terribly frustrating for others. But it’s also terribly frustrating for the person who is intimacy-phobic and does want your friendship but sabotages it despite themselves. The very nature of this anxiety disorder makes it difficult for them to explain what’s going on.