It's hard to admit, but sometimes even nice guys lie. This is especially true if you are in a new relationship and, although you really like each other, you are still getting to know whether he is the one for you (translation: is he honest with you even in the midst of an uncomfortable situation).
The fabrication doesn't have to be big, even bending the truth a little is really a lie in disguise. So, how do you get him to be honest about everything? It's all in how you approach him.
Keep the pressure off when discussing difficult topics. Men, in general, are more comfortable conversing while they are busy doing something with their conversation partner. (How often do men book an appointment with their buddies to go for coffee as opposed to a round of golf, fishing, or watching a sport?)
Ask him questions while you are cooking dinner together, working out, or walking together. Keep it simple. Choose an activity you can easily fit into the day, so you actually have a chance to initiate the conversation. Your questions will seem non-threatening to him and he will be more likely to open up to you.
Avoid interrogating him. Sit, stand, or be next to him. Don't position yourself across from him. It is a lot less intimidating to speak to someone who is next to you as a partner or slightly off to one side, rather than head-on, as if engaged in a battle.
Ask him open ended questions instead of stating accusations. Accusations will close him down and put him on the defensive. Asking for more information so you can understand where he is coming from will help him open up and feel relaxed enough to stick to the facts. Instead of saying,"I hate it when you ... " say, "Why do you ... ? It really makes me feel hurt." Instead of "You always ... " say,"Is there a reason that you want to ... ?"
Once you have asked the question, keep silent and wait for the answer. Don't keep asking questions, it will give him time to think about what to say. You want him to give you an answer that is truthful and not tailored to what he thinks you want to hear. It's your turn to listen, keep calm, and really try to understand his point of view.
Unless what he has said is a deal-breaker for you ("Yes, I did sleep with your best friend"), keep in mind that he has been honest with you and that is truly an act of love, even if it causes a temporary glitch in the relationship. And that is the kind of a guy you deserve.