"Umm... Fascination romances are definitely the shortest. The- There's a quote about this that I'm going to mangle. Lifepartner romances are like stoves or hearths. They need to be constantly maintained but serve a useful purpose, an essential tool and foundation stone of a good life. Fascination romances are like fireworks- All glory and spectacle, to fill the heart and mind with joy and light and wonder, but ephemeral. Know that the festival show shall end. Indulgent romances are like unto candles, burning steady and slow deep into the night, but all candles eventually turn to worn nubs. 'Blessed indeed is the woman who finds a man who lives well with her, who thrills and enthralls her, and who comforts or succors her, all three, who also fulfills the myriad smaller joys that the three do not capture. For most of our fragile souls, we take reflections and shadows of this perfect whole from many others, and try to assemble them to that purity, sharing and being shared. We fail, but we yearn for it none the less.'
...Sorry, I know that's not quite what you asked. Romances aren't - permanent. Especially fascination romances. But marriage is. Marriage persists past romance, even if all the feelings are worn to nothing, the fact of the marriage remains. That's kind of important. It's... An ancestry thing, a connection to the whole... As for how romances start... You... Talk to people, flirt with them," she does an ear-flick and glances away. "Touch them, get involved... Lifepartner romances are often more - practical. Found, not pursued. You realize one day that, oh, we're in a lifepartner romance aren't we. Umm..."