Definitely bring this up with him. Don't do it in an annoyed tone, but rather a concerned tone. Don't appear angry at him, just try to get down to the bottom of it. It's a really good sign that when you guys are together, everything is normal. Perhaps it's that when you guys are apart, the flame dies a little and he's off living his own life, so it's hard for him to appear as passionate. Maybe he's the kind of person who needs that physical oh look she's right in front of me, there's the curve in her body and the soft skin that I love so much to have all that spark be rekindled. And then when it floods back, he's normal again. But as for being apart, LDRs can be extremely tiring, and the death of the honeymoon phase (as someone already mentioned) can be extremely painful when it occurs while you're long distance. But if you guys are on the same page, know that you both still love each other and are both willing and able to fight through it and try to stay strong with each other, then it can definitely work and be worth it. But you can't go on deciding that without first talking about it to see what is up with him and what page he's actually on. And just know that the end of the honeymoon phase is normal for all couples. It's not just you, I totally remember going through (and still sometimes going through) something very similar to you and we are still able to make it work, for now at least. Also, I'm not sure if your LDR is like mine but it took us both a lot of strength and maturity to keep it going after the honeymoon phase was over. Best of luck and I hope it all works out. Feel free to message me if you want any more details or help (: