Twilight Sparkle x Flash Sentry
The two had a very good relationship, almost never fought.
They started dating when Twilight took over the lathe.
Unfortunately, when Twilight discovered she was pregnant, Flash Sentry died working in the royal guard.

Twilight Sparkle x ???
This is a relationship that does not have much information, the partner is the queen, she is not a public person and wants to keep it that way.
What is known about their relationship is: they've been dating for a year, it's a girl, they have a healthy and good relationship.

Sweetie Belle x Spike
the two have been dating since they were teenagers, but for lack of methods not to get pregnant, Sweetie Belle was a pregnant filly.
Rarity took over the child, putting neither of them old enough to be country, and they wouldn't be good country.

Fluer de Liz x Capper x Rarity
The three have one of the most talked about relationships in the kingdom, it was a big deal when it became public that Rarity was dating two people.
The three are very fond of talking about their relationship, so as not to give a negative impression about the trisal.
With Rarity adopting her niece, they had to get married so the little filly would have a good childhood. a while later the couple's twins were born.
Fluer de Liz says the best decision of her life was to give partners a chance

AJ x Troubleshoes
They were never really in love with each other, but due to a sudden pregnancy, the two tried to make the couple work. But after a few months before the filly was born they divorced because they couldn't hardly look each other in the face.

Fluttershy x Applejack
Fluttershy has always been in love with AJ, but would never have the courage to reveal it. When AJ started to feel the same way about her, she felt really weird.
They are the one with the best relationship, their daughters are almost the same age.

Troubleshoes x Limeston Pie
the two are kindred spirits, although they don't seem to have a good relationship, they have a great relationship. Although they prefer to keep the relationship non-public, Troubleshoes says he always hated the cameras and didn't like the feeling of being judged as in AJ's (by the public) relationship.

Rainbow Dash x Quibble Pants
form the last to be together, because Quibble was dating for a long time, they soon after starting dating got married (5 months later), they looked like soul mates so connected they were.

Pinkie Pie x Cheese Sandwich
they had a good relationship in their youth but changed a lot in adult life, which made them separate, despite that they have a daughter together.
Cheese Sandwich took custody of the pony, pinkie never got a chance to see her unfortunately.

Pinkie Pie x Party Favor
they are an Illarian couple, arguably the least public besides Twi.
They travel the world bringing fun to everyone.

UPITIF (Union of Ponies is True Friendship) Belongs to me SelenaVivacity and PixieSimm