Church window

Photo: Thinkstock

3 of 8
Mistake #3: Believing in the 15-Year Immunity
We've all heard of the Seven-Year Itch, but equally treacherous is a belief in the 15-Year Immunity. Just because you've been together for a long time doesn't mean you're beyond trouble. Maybe things aren't going so well and you tell yourself it's just a rough patch—once this stress is past and that issue resolved, your relationship is destined to return to greener pastures. This rough patch isn't Real Life, is it? Long relationships aren't always pleasant, right? Besides, you've been together forever. But if you want to hit the 50-Year Jubilation, you've got to overcome your belief in the 15-Year Immunity and dive in and fix what's not working.