Is this push/pull behavior with my ex? And why?

So I recently contacted my ex and we hooked up after 6 months. We have done this before, off and on, since he broke up with me in March. It seems after we get together and spend time together, he'll "disappear" and never keep in touch. But after a few months, he'll become more open with me, like answering texts, and phone calls, and ultimately wants to hang out. I have always kept the line of communication open with him, and have always respected his space. I've read about this behavior and I'm beginning to wonder if this is how he deals with how he really feels about me. If he's confused about his feelings for me.

Has anyone done this with their exes, or has anyone experienced this type of withdrawal with their exes after spending time with them? I would think if you were completely over them and have moved on, you wouldn't be doing this. Am I right? I would appreciate your views on this!
Is this push/pull behavior with my ex? And why?
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