I wish I wasn't just temporary

I wish he would stop talking about me finding someone else.
I know he felt bad for bringing it up last night.
It was really a bad time to do that.
He had taken me very deep, in my mind, I was there, in the room, being claimed by him just as he was describing. Submitting to him utterly and completely. I was his 100% no question in my mind.
Then, he reminds me. It's only temporary.
:'(
It's just, how can I give myself to him, when he keeps reminding me that our relationship is "just for now".
He keeps saying how he wants me to find someone else to love.
It makes me pull back from him.
It makes me afraid.
It makes me sad.
I do understand, he doesn't want me to be lonely, and he wants good things for me, I mean rationally, it makes perfect sense and I get it, appreciate it. But emotionally, it hurts.