When your Partner Lies

A number of years ago some university did a study on how often people lie. Please forgive me for I only vaguely recall the details of the study but it was remarkable how the number of times a person who "never lies" actually does lie - at least five times a day. It made me stop and think about how often I lied in a day and what I could do about it.
Completely eradicating lying usually requires completely eradicating fear, which is obviously the compelling motivator for intentionally misleading someone.
There is also the question of what actually constitutes a lie. If you saw somebody running away from some bad guys and the bad guys asked you which way he went would you be called a liar if you misdirected them?
So, in a relationship there are broadly two categories of lying: one is where the partner is protecting them self and the other is where the partner is trying to protect you.
Your question about whether your partner will lie to you again has everything to do with their level of self confidence balanced against their determination to be ethical. Because even those who are not fearless enough to always tell the truth may have a high enough regard for ethics to tell the truth even when they are frightened.
The bottom line is for you to accept the fact that a person will not attack their own personal defect (in this case lying) because you ask them to, no matter how important it is for you. Until that person, or any person, becomes painfully aware of the negative ramifications of their flaw, and sees it in many aspects of their life, they will not
have the ability to change (I go into great detail about this in Lessons For A Happy Marriage as well as in the new book I am writing for newlyweds). One of the greatest traps people walk into is thinking the person they love will change for them.
Soul mates are not always good soul mates; having long-standing relationships from the past creates familiarity but does not mean the relationship was necessarily healthy or unhealthy. Using common sense to really get to know somebody is the safeguard against revisiting unhealthy relationships from previous times.
Trust what you see as well as what you feel so your future children will be safe.