Whenever I feel down I try to redirect those thoughts into some new thing that I can do now. Nothing is ever 100% negative. Find those positives, dig them up and display them.
I get through by getting into every single thing I couldn't do before. Just like when I turned 18, I went to every place I could find to get carded. Even a great relationship is work and compromises are made, and it's hard to find the time to do all the things.
This weekend I dug out my trip collection I wasn't allowed to display. I pulled out old photos and hangers that didn't make sense for our blended family but now it's just what I want. I bought some used golf clubs. I rearranged the whole house to suit me (and to fill in the empty parts).
I'd bet your dog never seen either the snow or the beach, so take a whole trip just to do it. Learn to play drums. Spend hours at a bookstore. During a bad breakup some years ago, I volunteered for a campaign and went knocking on doors. Not only did I not get shot but I made some friends, too.
Revel in this phase. Because this will also pass and you'll find something else eventually (if you want to). I'm trying to be the most single I can be to really appreciate this time and learn from it.
You know, looking back at my life so far I realize.. all of my best stories were from my single days.