Hey Lexy. Thank you for your question and background information to your situation.
Without question, long distance relationship are the toughest. Pam and I met in similar situation, with her in Cape Town, South Africa while I was in Brisbane, Australia.
The distance does get the imagination going wild on all sorts of situations where you're unable to physically touch and talk to your partner. That same situation can also improve a relationship that's starting out too since you're avoiding the sexual tension and having to concentrate on the process of really getting to know and units and the other person.
After 3 years, you must have a fundamental feeling whether he is basically an honest person and I think you're saying that he is.
Relocating your entire life is one huge step to take too, understand that. It might well be that he is internally questioning what he's about to do, by moving to a different country. That can be stressful for anyone. Combine that with new job and the insecurity attached.
Anyway, have you thought of slowing things down so you both can take a breather, with the view of taking stock of the situation? It would be a terrible waste of relationship energy to throw things away due to long distance misunderstandings.
That said, lying is something that needs to be well and truly sorted out. It's the worst killer of relationships and if yours is going to survive, you guys need to have clear guidelines as to what's acceptable and how to deal it situations that arise that might cause anyone to lie. Truth, as painful as it can something be, is always the best policy.
Unsure if that all made sense, Lexy. Please do reply back with ANY questions you might have.