You have your own reason not to be seen by your friends or spouse maybe.
To prevent someone to find you on TrueLoveJapan website, you can type the Email of that specific person even if that person is not registered yet.
And if the person that you wish to hide yourself from suddenly register and try to find you, it will become impossible, your profile will be invisible.
Go in Setting → Scroll down → Black List → Enter the email
As a note, none of the TrueLoveJapan members are visible outside of the website unless you request it. Your profile will never appear on any search engine such as google search, yahoo search, bing search and so on ... Not even on Facebook.