Hiro and Zero Two were lovers and partners that fought against the Klaxosaurs. They had originally met as children, but Zero Two had her memories wiped whilst Hiro did not recognise her when they met again.

Does Zero 2 have a boyfriend?

Her relationship with Hiro became much better and Zero Two came to cherish and love him more than anything, to which she finally understood Hiro's words where he wanted them to understand each other.

Does 002 and Hiro end up together?

As strange as it may be, Hiro and 002 are considered to be married in the series. While there was no traditional ceremony, this happens when 002 flies through space wearing a wedding dress and announces that the two are on their honeymoon together.