First off, congratulations! Being in a committed relationship for a year is a big accomplishment. You sound very upbeat and I am grateful that you are doing well (except for this latest issue of course).
Relationships progress in four stages. You are just past stage two: investigatory exchange, a long stage where you find out everything you can about each other.
The stage you both are in now, stage three, is called trust development and attachment, and is a long stage as well, but if you get through this one...the great news is that this is definitely a quality long term relationship and has a great chance of success!
Now, the disturbing thing about this third stage, the one you are in now, is that the partners often do not tell each other the full truth until they hit this stage. Deception, to try to make the other person like them more, is common at the end of stage two and here in stage three, the more insecure partner, they are more likely to lie and try to make you think better of them than they are. The stage resolves when this lack of truth is discovered and dealt with. Welcome to were you now are!
Yes, this lying behavior is wrong. And, truth is always best. But it was done to make you like them more, and as twisted as that logic is, is it done because they really care about you. Many, many people do this and it is considered by most relationship experts to be pretty typical behavior for the stage. Interestingly, just like what happened to you, it causes the first real fights and conflicts. That is expected, and totally normal. So, one thing you need to know is that this is not unusual at all. It happens, just as it happened here.
BotXXXXX XXXXXne is that you were hurt by this lie. But, you did the right thing and explained that lying is a deal breaking event. You also made it clear that you expect more, and now you are wondering, can I trust this person and how do I get over this?
I would suggest a couple of things. One, know that males tend to be very much forgive and forget it types. We struggle with the fact that almost all women cannot just forget hurts. He will have to mature and accept that you were hurt. He will need to see that each day he has to earn your trust again. That is expected and also normal. It will not be easy for him, but that is what it will take and learning this is a part of the journey and there is no easy way to make it happen except to learn about this pattern. He is in for some life changing insights about himself and women. Bluntly, let him squirm a bit in this. He needs to mature in it and that is a part of the process.
To let some of this go yourself, choose a moment in time (like Sat at 5pm or any marked period of time) and say to yourself: I know he lied. He hurt me. But I am not going to collect on this emotional debt. He is free. Now, again, you will not feel this. This is a cognitive choice. But as you do feel mistrust and anger brewing about the memory, you remind yourself that at such and such a place and time you let this debt go. It takes a bit, but by doing this the hurt diminishes a great deal, faster than if you did not.
For him. His insecurity is showing up here a lot. I would guess that he is very afraid of losing you. But his insecurity cannot be expressed as lying. He needs to be told that you will accept him far more if he relates the facts and truth, and not a smokescreen of deception.
I often recommend at this point, that because this relationship is getting serious that both of you talk with a couples counselor. That is not over the top by any means as we are complex creatures and have much baggage in our lives. It is not silly or too much. It is preventative and helpful. It is not about him...which he may think at first, but about you both. And it helps tremendously. A few sessions is all it usually takes to set better expectations and communication.
I will say that you sound like you are doing very well. This pattern is not atypical and almost all couples get through this. And, you are very close to making this relationship a life one...a great thing for you both. I think that what I have heard, although difficult, is expected and will work through. Steven