What about loneliness?

I live in a two bedroom apartment. I also live alone. Lots of people think it's really strange that I have this whole extra bedroom, with no one living in it. I'm not really sure why I decided to rent a two bedroom apartment. I guess I wanted to have the space. And at some point, I thought I would like to have a room-mate. Or at least, there was someone I had in mind.
So now I have this apartment with plenty of space and an empty room. I keep the door closed. There are a couple of reasons for this. One reason is that it helps keep the place warmer, and it is heading toward winter, after all. The other is that if the door is closed, I don't have to see an empty room. I don't have to be reminded of the fact that there is emptiness in this place that I call home. And it does feel like home, I don't mean to be dramatic. I'm happy here, mostly. But I'm also lonely, lots of times. Having space is great, and there aren't that many people that I would trade the empty room for. But there are a couple. And even though I like my space, silence can sometimes be so loud. Being in a space that is so utterly empty, the sound almost reverberates around you can be disheartening to say the least.
And for the past week or so, I've seen what this place would feel like with another person, another body. And I like it. I like getting up in the morning and knowing that there will be someone there to greet me, to talk with (and trust me, I'm a talker). There's only a couple other times in my life when I've felt this same kind of peace and contentment and one of them was this summer, while I was staying with boyfriend. Waking up next to him each morning was somehow beautiful. It wasn't that every morning was special for any particular reason, especially since we had a pretty stable routine, but there was a sense of safety and security and goodness there. It makes me miss him, and the time that we spent together and the simple and random things that made our life together for those couple of months so sweet.
Which leaves me feeling lonely. Feeling abandoned. Feeling sad. How do you feel fulfilled when you know that there's something, some piece, missing from your daily existence. I still have all my space, and it's nicely organized and nicely decorate now, but I also still have that empty room.
And that empty space in my heart.