If you consider your significant other as your best friend, then they will most likely support you in whatever you do, they always make you feel special, they always make time for you, they will always be there when you need them the most, but most of all, they love and accept you no matter what.
Unfortunately, there are downsides if you consider one another as friends despite being a couple. Some relationship experts say that there will always be disadvantages of every viewpoint, because there are no perfect relationships.
Experts say that one of the best ways to stay together as a couple is by becoming friends as well. One specific downside is when you get into a disagreement or a misunderstanding, you may confide with your other friends about it, but you know that no one knows you and understands you as much as your partner.
Experts say that this downside is inevitable, which is why you must always have an open mind and think of everything to save the relationships. 
This is why most old couples believe that in order for a marriage to last a lifetime, when something gets broken, the couple must work together and find a way for them to fix it, instead of throwing everything away.
Keep in mind that your relationship is a treasure that can only be guarded if two people work together to keep it safe.