One thing that i've learned over the years is this: In a relationship - regardless of the type of relationship (friendship, sibling or romantic, etc) - if you don't have trust, you don't have anything solid to hang on to.

If he's constantly lying to you, then he's got a reason for that. Perhaps he's not liking who he is and doesn't believe that if he shows his true colors, you won't want him anymore, so he feels the need to lie?

Regardless of how you look at it, the two of you need to have a serious conversation on the topic of trust. He obviously doesn't trust you. If he did, the truth would come from him, not lies.

You don't trust him - because you've uncovered multiple lies over an extended period of time.

It WILL be a tough conversation for the both of you. Getting through lies in a relationship is very hard to do... not impossible though.

I wish you the best of luck with your situation!