I don't see how the results of spending flower gems is in any way related to a gacha which can only paid for by Nutaku gold. If they save their flower gems for the bride gacha and don't get a bride, that's just the breaks of being FTP. If, however, someone spends Nutaku gold on the bride gacha and doesn't get one, only then is it regrettable that they didn't take advantage of this guaranteed one.