Advice?

I’ve been in an LDR for 3 years now, and I’ve been positive most times in our relationship, with high hopes that we will close the gap. I’ve done my research, on our options and I’m just waiting for him to finish his studies. But recently, had a conversation that made my hope less than it was before, he said he’s second-guessing with our situation. I suddenly felt different about things and my feelings slightly changed. Does this really happen in LDR? How do you both recover?