A new app has launched for iPhone that lets you keep track of your love life by illuminating positive and negative patterns.

Author Linda Sivertsen's husband left her for another woman after 19 years of marriage. She didn't see it coming, even though the relationship's bad days were more frequent than the good ones. Now, roughly six years after her divorce, she has helped release an app that lets you identify the good days in your relationship and then compare them with the frequency of bad days.

The Boyfriend Log is a new app that - at first blush - seems a bit obsessive. Although the target audience is women, men can easily use the app as well to journal every single day. You don't write what you ate for breakfast or where you went shopping however. You simply take note of your mood. If you're having a lovely date night with a spouse or significant other, mark it down. The Boyfriend Log will assign that evening a little green sticker of sorts.

Alternatively, if your loved one ditched you for friends and hasn't called you all day, you can tell The Boyfriend Log how sad you are feeling. The app will then assign that day the colour blue - for sadness, naturally. After a few weeks, months, or even years of doing this, you'll be able to clearly see whether your relationship is flourishing. If you have more angry days or sad days compared to good days, you are likely in a co-dependent or unhealthy relationship.

In fact, Sivertsen used the method behind The Boyfriend Log to navigate out of yet another sour relationship shortly after her husband left: "Seeing is believing, and clarity is queen. This time I was accountable to the patterns. I could trust myself to be my own eye-witness. And I knew what I needed. When the next relationship came, truth was on my side. And I found greener pastures," she said.

Sivertsen has now been with another man for about four years - and she credits The Boyfriend Log for that relationship's success. She said the app can also assist people with keeping their relationships fresh, because it gives visual clues when, lets say, they are having lazy days and might not be giving their relationship the same amount of attention that they did in the beginning.

You can download The Boyfriend Log for iPhone starting today. It costs $1.99. Watch the video above to learn more about the app, or you can watch the video below to learn more about Sivertsen. There's also a gallery of screenshots available below.