"Was it a secret? Let's all just enjoy life & have no regrets :)"
Although Haynes has never officially come out as gay, his sexuality has frequently been the subject of debate. Back in 2013, gay Arrow costar, John Barrowman grabbed Haynes' hand for the paparazzi in what appeared to be a flirtatious joke. Even before that, Haynes had posed for a very homoerotic shoot in the March 2006 issue of XY Magazine.
10 years later, perhaps Haynes has finally become comfortable enough in his own skin. Since most celebrities seem to already be out before finding themselves in the limelight these days, the pressure to bother with a public statement seems to have dissipated.