A relationship expert believes that a Reddit user is justified in not attending their younger sister's wedding to her ex-fiancé.

The woman's decision not to attend her sister's wedding is understandable given the highly unusual circumstances, according to a relationship expert and Reddit users.

"AlisonVio" posted on the "Am I the A--hole" subreddit on July 8 asking if she was wrong for refusing to attend her sister's wedding after her sister secretly dated and got engaged to her ex-fiancé.

The woman advised readers to brace themselves, as the post would be a thrilling ride.

She stated that she is a 28-year-old woman who was engaged to "Mike" for two years before their breakup three months before their planned wedding last summer.

"The woman discovered that he had been cheating on her with someone else, so she immediately called off the wedding."

"After the breakup, Mike moved away and AlisonVio believed it was the conclusion of their relationship."

She was heartbroken, but she slowly started to move on with her life until last month.

AlisonVio wrote: "My younger sister 'Lily' (25F) called me with exciting news and invited me to her parents' house for dinner to share it."

"My head was spinning. I felt like I was going to pass out."

As she continued, "Upon my arrival, Lily and my parents were all smiles. However, she dropped a bombshell: she's engaged to Mike."

"I felt like I was going to pass out as my head spun." - AlisonVio wrote of the shock.

She discovered that Lily and Mike had been secretly dating for a year and were now engaged, and her parents had known about it for months but chose not to inform her.

AlisonVio remarked, "They believed I would eventually be content for them."

Her sister, however, tried to justify her actions by stating that she and Mike fell in love after the breakup and that their relationship was meant to be.

"AlisonVio expressed feeling betrayed on multiple levels and stormed out after telling them she didn't want to be involved in their wedding."

This did not go over well, she relayed.

"I have been receiving numerous calls and texts from my parents and Lily, who accuse me of being selfish and overreacting."

AlisonVio stated, "The woman wrote that true love is rare and she should support Lily's happiness. Now, the wedding is imminent, and the pressure is mounting. My parents have threatened to cut me off financially if I don't attend."

Even though Lily asked her to be her maid of honor, she said she wants to mend their relationship.

I feel torn between preserving our family dynamic and addressing the hurt and betrayal I experienced.

Her friends, conversely, are split about what AlisonVio should do.

While some friends believe I should attend to maintain peace and demonstrate my resolution, others are outraged and assert that I am entitled to my anger and to keep a distance.

"It's the wedding of her ex-fiancé who cheated on her."

"What do you think, social media users? Am I the asshole for not attending my sister's wedding after she secretly dated and got engaged to my ex-fiancé?"

Nicole Moore, a California-based relationship expert and certified life coach, stated to Planet Chronicle Digital that AlisonVio is justified in not attending her sister's wedding because it is not only her sister's wedding but also the wedding of her ex-fiancé who betrayed her.

It's not surprising that this woman reacted negatively to attending the wedding of someone who cheated on her, as most people would have similar feelings.

Moore expressed her concern that the woman's sister and family were treating her feelings about the engagement and wedding as less important than their own "true love."

Moore stated that the absence of recognition would make anyone hesitate to participate in a family gathering.

Reddit users overwhelmingly agreed that AlisonVio is justified in skipping her sister's wedding, despite her parents and some friends believing she should attend.

"Some friends think I should go to keep the peace and show I'm over it, while others are appalled and say I have every right to be angry."

Almost everyone in the more than 1,200 replies to the post agreed that AlisonVio was not wrong for not wanting to attend.

Mike cheated on you and broke your heart, and now he is with your sister and they hid this fact from you, as stated by Reddit user No_Construction_1096 in a top reply to the post.

The same person wrote: "They drop a bomb on you, accuse you of being heartless for not believing in their 'true love,' and Lily even dares to ask you to be her maid of honor."

"I can predict that if Mike cheated once, he will do it again."

AlisonVio should consider going low-contact or non-contact with her family in the future, based on their future behavior towards her.

Another Reddit user expressed disapproval of Lily's choice to date Mike.

"I can't fathom ever wanting to date someone who hurt my sister. If you harm my sibling's feelings, you are out of my life forever. There is no chance of a relationship with you," said user "readthethings13579."

"Lily is a bad sister for considering a date with the man who betrayed her sister, let alone marrying him," the same user stated.

And one Reddit user had a rather nefarious suggestion for AlisonVio.

KanaydianDragon" stated on Reddit, "My petty heart was saying, 'Be the maid of honor and give a toast about our romantic history at the reception.'

Who needs a family like this, even if it's a bit scorched?

AlisonVio will not attend the wedding, but she will take time to process the event and determine if she can find peace with it.

AlisonVio should speak to her sister and parents about the upcoming wedding after she has more time to process her emotions about it, Moore advised.

The woman may choose to attend the wedding but not serve as a maid of honor, allowing her to leave the reception early if it becomes overwhelming.

Planet Chronicle Digital reached out to the original poster for comment.