The answer is quite simple as to why random people technically 'flirt' with others they don't know in game, it's the internet. Before, anyone goes and jumps up and down saying, "BUT WE'RE TALKING ABOUT THE GAME," hear me out. On the worldwide web, you're anonymous since no one will ever know who's behind the other screen or so thus giving them the idea of acting freely and doing what they want. When most users do sign up or so, they usually don't use their real information (age, sex, location) since it'll be hard(er) to identify who they are. This can be applied to the game since honestly, how many people actually play this game and has a dozen or so friends at their common place (school, workplace, etc.) that they know and are acquainted with?
Anyways, it is inappropriate to take the what happens in games seriously and insult what they do in game. What if they do have friends but want to go to a 'mating center' for the hell of it? Besides, who'll take romantic relationships on a multi-player game about roleplaying as wolves and lions seriously? I understand as to why there isn't a 'dating center' since wolves and lions do not date and it sort of ruins the purpose of roleplaying realistically if animals mate, not date (and they're not actually forming a relationship..) Besides, if someone needs a mate for a roleplay and sees everyone is taken, a mating center is a good place to go to. As -Blacki said "Let people be people," but let me add, do not take this game seriously and don't be bothered by what other people do, it'll only make some situations tense in the future.