It's as if they stick together. They go into the hotel together, they sit alone in the same plane, when the other takes another aircraft. They go to the same pubs together and they're doing more together than before.
Although Harry has previously (before he became famous) been with guys. He open walking to the bars for gays and he never pronounce "she" when they're talking about partners. Harry always says "person" and never puts gencder on a partner.
Niall is secretive about his private life. He has been with girls (Barbara and more) but I don't see the glow in his eyes. He doesn't love them and he doesn't seem to want to be more, more than as a friend. He socialize much with guys. Many of his personal photos are with the guys and Niall. Not at him with a girl friend.
Who knows? Maybe there's a small Narry out there?