"话说爱情合久分,分久必合."怎么用英语翻译

As the saying goes, love together a long time, and will certainly separate. Separate long will together

There'll be separation after long unity and vice versa in love.

it is said that love which u get together for a long time u will be parting ,conversely if u are parting for a long time ,u will get together again .
i don't make sure that it is quite right ,but hope that my answer can help u .