1. The best partner is your best friend.
When I hear "relationship goals," I automatically think of Jim and Pam. We waited over two seasons for Jim and Pam to move from friends to lovers. There was a reason why they had the healthiest and most admirable relationship: they were both in love with their best friend.
2. Never give up on love.
Michael Scott fell in love at first sight with Holly Flax. After she was forced to transfer back to Nashua, they were forced to break up after a few weeks.  Michael never really got over Holly and had no control over her dating T.J. When Holly moved back to Scranton (three seasons later), she gave T.J. an ultimatum. If you've seen the show, you know this ended up as a happy ending for Michael, and they got back together and became engaged.  See what happens when you don't give up on love?
3. Don't change who you are in exchange for love.
We see a few examples of this in "The Office." Michael gives into Jan's uptight personality as she didn't allow Michael to be the goofy, spirited kid he is. On the other hand, Angela was always striving to find someone who made her look good on the outside. You shouldn't have to force yourself to love someone. Angela did that with both Andy and "The Senator" until she found happiness with Dwight, who accepted her for who she was.
4. Some things should be kept private.
There were countless times where couples fought in front of their co-workers. Public arguments not only make people feel uncomfortable, but they usually force your friends to take sides. Take "The Dinner Party" episode for example. No one wants a relationship like that.
5. Know how to approach the opposite gender.
Andy Bernard was too passive when it came to expressing his feelings for Erin. Because of it, he lost his chance with her multiple times. On the other hand, Michael Scott came across as too bold and confident at times (i.e. when he photoshopped his face on Carol's ex-husband's face in the family photo).
6. There's someone for everyone.
There's two keys to this one: Patience and humor. Most of the relationships in this show formed after seven, eight, or even nine seasons. And each couple that formed shared the same type of humor (Jim and Pam, Michael and Holly, Erin and Pete, etc.).
7. There's more to relationships than sex.
Dwight and Angela's scandalous (and sometimes disturbing) affair was on-going throughout the entire show. They always had sex, but never could figure out how to have a lasting relationship. It wasn't until they both realized that relationships aren't based on sex, but rather the admiration and love for the other person.
8. Be bold.
In one of my favorite episodes (Beach Games), Pam goes out of her comfort zone and walks over fiery coals. She then gains confidence to admit her love to Jim in front of everyone, kick-starting their official relationship. They may have never dated unless she was bold.
9. Honesty is key.
We can surely learn a lot from Jim and Pam. Jim went out on a limb to tell Pam (when she was engaged to Roy) that he loved her. In the long run, it paid off for him. On the flip side, characters such as Angela and Jan endured tough breakups due to affairs. Don't use someone (like Jim kind of did to Karen) in hopes to get over your previous love. Be honest with your partner.
10. You should always be with someone who makes you happy.
Was this a common theme, or what? Kelly and Ryan (at first), Michael and Jan, Andy and Angela, Darryl and Kelly, and most explicitly, Pam and Roy. Roy was always looking at other women, never paid Pam attention, and they never seemed happy together. Happiness is key to a healthy relationship.
