Question: when he backs off from you, do you bury him in texts? Or do you give him his space? If you're clingy, as you admit, I would imagine that you probably continue to text him when he's backing off from you.

Relationships need space to breathe. He doesn't need to always be in control of when you're in touch with each other, but you do need to allow space and room in between texts and in between seeing one another.

He says he needs to be able to miss you, which indicates to me that you may be smothering him. MAYBE. I am just making an assumption based on what he said. Him backing off and not texting you may be his way to regain his space and to miss you. He may be sensing and picking up on your clinginess - they usually do.

Relationships are a balancing act of being in touch, seeing one another, but also allowing for independence from one another and breathing room.

Also, you said you're dating to marry. Do you know that he's the one? Have you talked about it? Does he wish to marry you?

Do you have your own hobbies and friends? When he backs off and needs space, can you give him that space and do something else with your time?