Relationship (The Sims FreePlay)

Relationships are a key factor of communication between Sims in The Sims FreePlay. There are some differences between the relationships system in The Sims Freeplay and the rest of the series. I been trying for my sims to be in a romantic relationship with each other but it seems I can't it keep going from friend to best friend back to friend to best friend back and forth

Friendly Relationships
There are several stages to friendly relationships. To create a friendly relationship between two Sims, have them do actions such as 'Be Nice', 'Bro Hug', 'Be Funny' or 'Chest Bump'. As a pair of Sims advance through each stage, a certain amount of Simoleons and XP will be received. The number of unlocked interactions depend on the relationship between the Sims. When Sims are acquaintances, they can 'Hand Shake'. Becoming friends will unlock the 'High Five' interaction, good friends will unlock 'Bro Hug' interaction, and best friends will unlock 'Chest Bump' interaction.
 * Acquaintance + 150xp
 * Friend + 150xp
 * Good Friend + 200xp
 * Best Friend + 250xp

Romantic Relationships
Preteens and older are able to have romantic relationships. There are several stages to romantic relationships. To create a romantic relationship between two Sims, have them do actions such as 'Be Romantic' or 'WooHoo' (only available for partners, engaged and married). As a pair of Sims advance through each stage, a certain amount of Simoleons and XP will be received. Although Sims have to be level 6 to have a romantic stage such as dating or move in.
 * Budding Romance + 100xp
 * Date + 150xp
 * Partners + 150xp
 * Engaged +200xp
 * Married +250xp

When two Sims become partners, the option of 'Propose Marriage' is available. You will be prompted to buy an engagement ring. The higher value the ring is, the more likely the Sim will accept. But if the price of the ring is cheap, the more likely the Sim will say no to the offer. If the Sim accepts, they will become engaged. The two Sims will not be married until they move in together. A married couple can buy a crib and have a baby (click on the crib and you will be prompted to create the baby).

If a married couple breaks up, the player will need an Eternity Ring to get them back together, which costs 10 LP.

Unfriendly Relationships
There are several stages to unfriendly relationships. To create an unfriendly relationship between two Sims, have them do actions such as 'Be Rude' and 'Complain'. As a pair of Sims advance through each stage, a certain amount of Simoleons and XP will be received. Two Sims who dislike each other can offer each other 'Fake Hand Shakes'. When two Sims become enemies, the 'Rude Hand Gesture' interaction becomes available, and when two Sims become nemeses, they will be able to slap each other. You will get XP and Simoleons each stage you go
 * Dislike +100
 * Enemy +150
 * Nemesis +200

Different Colored Interactions
There are four different colored interactions available for Sims to perform.
 * Green interactions will cultivate friendship between Sims.
 * Purple or  Pink  interactions will cultivate a romance between Sims.
 * Red interactions will degrade the current relationship and eventually give Sims the option to break up if they are romantically involved.
 * Blue interactions mean that they were romantic to each other but now are acting friendly or the other way around.