You know... It usually doesn't bother me...

Lately, I've been bombarded with other peoples relationships... Friends celebrating anniversaries, people finding romantic partners, etc... I've been single for a long time, having a few "crushes" here and there but usually nothing coming of it. But it's never bothered me before tonight.... I don't know why but it feels like I've just been hit with a giant wave of loneliness. I can't say I'm a fan of this feeling. Anyone go through something similar? Any advice on how to deal with it?