I know it sounds silly but have you tried sleeping in a different room or on the couch for a night? I've never had a relationship but when I am in a very stressful situation and I'm having trouble falling asleep because of stress and worry or I'm missing someone; sleeping in a different room helps. I usually gather my duvet and a few comfy pillows and sleep on the couch. Oh... and if you're missing cuddling someone and I often feel lonely and wish there was someone I could cuddle inall - I usually just cuddle a pillow. It's not quite the same but it's better than nothing! Anyway... about sleeping in a different room; I don't know why it works but it just does (for me). Just a thought...