My parents told me that the way to have a long term relationship was to always have one person that still loves the other and hope that both parties don't “fall out of love” at the same time; that way there will always be one person try to keep the relationship together.
Relationships are hardwork but the good should outweigh the bad. My grandparents use to always bicker and fight but they were together for 49 yrs before my grandma passed away. My grandpa was-and still is at times- a wreck. When you're with someone for that long, you truly become apart of one another. 49 yrs has seen a lot of pain, innumerable fights, and loss of friends and family. I think the scars of dealing with these difficult times mend people together and make the bonds of your relationship stronger-- therefore, your relationship can handle more stress compared to what you may have been able to endure 5 or 10 yrs earlier.
Good luck on your relationship