My fiancé is in the Army and has a very high-level stressful job. He is currently in Korea serving, yet I am still home. This causes even more stress. My question is, is it normal for couples to often have arguments and heated discussions before getting married, especially when they are living in a long distance relationship (at least at the moment we are)?

Yes and I hope they have them all their life.

Not bad fights, but couples don't agree, and if you are heatly discussing, then you are talking and being honest how each feels.

The stress of being too far away for that time, a high stress job and you being alone and not having him, can cause trouble for the best couples