One True Love in Chinese / Japanese...

真愛 is literally “True Love” in Chinese.

The first character means “real,” “true,” and “genuine.” The second character means “love” and “affection.”

During the customization of your calligraphy wall scroll, there is a place to add an inscription. You might want that inscription to be your names in Chinese down the side of your wall scroll or perhaps just below these two main characters (just $9 extra). A nice gift to celebrate an anniversary or marriage!

真実の愛 means “true love” or “genuine affection” in Japanese.

The first two Kanji mean true, real, genuine, or authentic.
The third Kanji is a connecting possessive article.
The last character is love or affection.

我心真愛 is a slightly poetic way to express this sentiment to someone.

The meaning is “My True Love,” but the characters directly translate as “I/Me/My Heart/Mind True/Real Love.”

Note that Chinese grammar and construction are different, so this sounds very eloquent and artsy in Chinese.
In Korean Hanja, the third character should be written differently. Just let me know when you place your order if you want that version - it will still make sense in Chinese. This phrase makes sense in Korean but is not commonly used.