This is the nature of an LDR. There's only so much that you can learn about one another and experience together from a distance. There are countless subjects, both major and minor, to discuss between yourselves about each other - politics, religion, ethics, morals, beliefs, convictions, goals, aspirations, passions, influences, childhoods, views on children/marriage/etc, lifestyle preferences, ideal relationship preferences on both a large and small scale (large scale meaning what type of relationship you desire long term, etc and small scale meaning day to day life once you close the distance, etc), fears, hopes, dreams, memories. That's not even an all inclusive list.
But once you have exhausted most of those topics, which takes some time in and of itself, and perhaps occasionally during while you're yet to decide what comes next on the discussion list, you are left with merely finding things in your day to day life to discuss.
To echo the other reply, do not feel weak or insecure for stating how much you'd rather just be together and whatnot. My partner and I do this every single day, regardless of how much actual random communication or activity goes on. What you call boring and mundane, I call wonderful, peaceful, relaxing. And so does he. As such, we spend our days watching videos or playing a game (or both). That's it. That's what we do. Watch videos, play games, talk about our days for a brief minute before beginning activities, and occasionally discuss Reddit threads or whatever else we find interesting or come up with to talk about. Sometimes we'll share music, or silly youtube videos, etc, but for the most part we've settled in to the life we'll lead permanently. Neither of us could be happier with that.
But each person is different. If you're seeking ideas for things to discuss, I'd like to point you to the following:
As for the loneliness, it truthfully doesn't go away. I wish I could say it did. But that is the price we pay for having found a love so precious but so far away. Cherish having someone that makes you miss them so much. We'll appreciate each other all the more when we're finally together.