I heard once that glitter is the herpes of crafts, because once you get it on you you can NEVER get them off. I told a friend recently that I was like herpes, and no matter what he did he would NEVER be able to get rid of me(yes, I did just refer to myself as being like herpes). After a lot of laughter over such an absurd comment, we went along with our dinner.
That evening I did a little thinking, which turned into a lot of thinking over the next couple of days. In actuality, our relationship was like herpes. We ended up in each other's lives unexpectedly; we didn't realize at first what we were; we are not necessarily that good for each other, although I'm sure we could live normal lives with each other; and yet we just can't seem to get rid of each other. We have tried, trust me, but time keeps pushing us back into each other's lives.
It's a horrible metaphor, but go with it.