Coward writing (spoilers)
It was a fun little movie, but the writer(s) chose the easiest way out, even with the "twist" ending.
The character of Mikey is such a mismatch for Oona that there is really no question about his fate. He's 22 yrs old, crappy job, plays in a band, lives with 4 others and she's a 30yr old woman with good carrier and a stable life - without any gigs. It's set up for him to lose from the start.
A more daring approach would be changing the roll of Mikey to the one of Dan, played by Desmond Harrington, keeping the same premise; met through a blind date, lost wife, all that - but having the same relationship with Oona as Mikey. Even the trick with false timer could work as the character of Dan could choose to use a fake timer in order to "take himself out of the market" after the death of wife, until he runs into Oona, which changes everything for him.
That leaves us with Steph and her meeting someone that is kind and very decent, but not really a "pretty boy" per definition, someone maybe in the lower part of average looking.
Everything else would play out the same, but it would make the choice for Oona that much harder and hopefully deeper in nature. Does she stay true to her soul-mate belief or is she willing to sacrifice it when faced with "trading down" from Dan...