Wouldn't "Romeo and Juliet Syndrome" be more accurate if it was more true to the term by means of Shakespearean tragedy?
In all seriousness, everyone's dying anyway. You're dying. I'm dying. Everyone's dying. In a long enough timeline, the probability of survival is zero. Instead of mourning about the deaths of loved ones, it would make more sense to just remember those good times rather than just the bad and apparently horrible reality. It's absolutely pointless to even mourn them and it would be more reasonable to praise them instead because of they are now at their most peaceful. I'm sure as they decompose and become worm feed and a mold society, the last thing that they would want would be the loved ones that are still amongst the living to be wasting time just mourning over something so meaningless.
If they're gone, they're gone. As they say, they are in a happier place now. A place that is happier than anything that we could ever experience, but despite them beating the rest of us to the punch, all we have to do is live our lives to the fullest and just keep on living.
The reason you're feeling bitter is because you, like everyone else, are weak, but that's not necessarily a bad thing. The tears will dry and soon you will arise and overcome such futile emotions and glance at the picture frame that house a photo of your loved one with a significantly stronger sense of inspiration rather than depression to make your life more worthwhile.