
Not all families are a mom, a dad, and their biological children. Between breakups, sexual orientation, deaths, adoption, and a hundred other factors, family units come in all shapes and sizes. That is why a Reddit user is venting over his fiancée telling his sister he’s not her “real dad,” even though he’s had custody of the girl since she was a toddler.
The 24-year-old man recently took to the AITA subreddit to ask users to weigh in on a tough situation. Recently, his girlfriend – whom he just proposed to – corrected his 5-year-old sister when she called him her “daddy.” The repeated correction resulted in the girl bursting into tears, as the Redditor has not yet explained the complicated circumstances surrounding her custody. So, is he the jerk?
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The Reddit user gained custody of his sister when she was 2.
In late January 2025, the original poster, or OP, explained that his younger sister, “MJ,” was born when he was 19.
“My mom was a drug addict, stopping during pregnancy, but when MJ was about 5 months old she started back on drugs, dropping MJ off any place she could,” he detailed.
After a “long hard process,” the OP obtained full custody of MJ when she was 2.
“All this to say, I’m legally MJ’s dad,” he shared. “I’m the only dad she knows and she calls me dad.”
Recently, he proposed to his girlfriend, and things were going great.
In the Reddit thread, the OP noted he met his girlfriend, “Ida,” 24, about a year ago. They started dating not long afterward.
“I really thought I found somebody to like me and MJ,” he wrote. “Ida would always take MJ on ‘girls days’ and little ‘dates.'”
A few days before posting, the OP proposed to Ida.
“It seemed like everything was great until a few hours ago,” he admitted.
The OP overheard his fiancée telling his sister he’s not her ‘real dad.’

Recently, Ida was at the OP’s apartment having dinner with him and MJ. That’s when he overheard an upsetting interaction.
“I heard MJ say something along the lines of, ‘Your gonna marry my daddy and your gonna be best friend,’” he explained. “I thought it was cute until I heard Ida laugh and say, ‘He’s not your dad MJ,’ which caught me off guard.”
The OP continued, “I guess she thought I couldn’t hear her because there’s a wall between the kitchen, but still I don’t know why Ida said that. MJ was confused, as 5 year olds are, said I was and Ida kept correcting her until MJ started crying.”
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Now, he and his fiancée are fighting.
When the OP asked his fiancée why he said that to MJ, she reportedly replied, “She was going to find out eventually.” Ida also thought he was wrong for not telling MJ in the first place.
“I got mad and one thing led to another, I said some things I shouldn’t have, telling her she had no right,” he explained.
Ida went home but later was “blowing up” his phone text messages insisting he was in the “wrong.”
Before asking for the internet’s input, he shared, “I was gonna tell MJ I was her brother someday, yes, but when she’s old enough to understand. MJ is only 5, she doesn’t make sense of it.”
Reddit users all agreed: He is not the one at fault.
In the comments, Redditors concluded the OP was not the a–hole in this situation.
One person pointed out, “You stepped up and became MJ’s father when no one else would, and you’ve given her a stable and loving home. That makes you her dad, regardless of biology.”
The commenter added, “You were right to be mad, and you’re not wrong for protecting your daughter’s emotional well-being. If Ida doesn’t respect your role as MJ’s father, that’s a huge red flag for your relationship.”
Another Reddit user agreed the OP is not at fault but pointed out, “I think it’s time you have this conversation with MJ.”
The person pointed out that lots of books exist to help someone talk through adoption. “They even make books for little kids about how they are special because they are picked. I’d also start slowly with the story that her mom couldn’t take care of her and you wanted to,” the person added. “You can keep it all age appropriate, but it’s a good idea to start socializing this young. You don’t want her to be 16 when she finds this all out.”
Yet another Redditor warned, “You should not marry this woman if you want to be a good dad. I’m willing to bet that Ida told her on purpose. She wants it to be clear to her that she isn’t your daughter so she knows when the two of you have kids that they’re the ‘real’ kids and she was a charity case. I am also willing to bet she doesn’t want her to start seeing her as a mother figure, and that is another reason she told her.”
The person had more to say, adding, “Doesn’t seem like a coincidence that she told her this after you proposed. She figures she has you secured so she doesn’t need to play nice anymore.”
What do you think?
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