Hiro was the summoned man from the same world.
He and Kyoya shared the same origins and even though their summoning happened roughly at the same time, their destinies were different.
Kyoya's summoned purpose was to be Xaya's husband. She wanted a weak husband, but it was because of the events that happened before the summoning. Things got different because of Kyoya and he turned out to be an even better husband than she could've imagined.
One also could argue that Kyoya was exactly what Xaya's unconsciously wanted.
Of course, Kyoya became 'the husband' literally which was not something she had control over, but there was no marriage with only happy times. The most important was that the husband could turn worse times into happy times with the love blooming between them.
