I will probably get a lot of flack for this so let me start with the usual comments I anticipate: no, his daughter does not have sensory issues, is neurodivergent, or any other mental disorders that might affect her eating habits.
With that, I (28F) am a single mother to one kid (8F) and have been dating and recently engaged to a man (27M) and his child (8F). The first half of us dating, he was going through a court battle and only had every other weekend with his daughter. We mostly planned activities as play dates and his daughter took a quick liking to me and I to her. Our daughters are best friends and very excited to become sisters.

Once he was granted 50/50 custody, we started spending more time together and I noticed his daughter is an extremely picky eater. As in, favorite foods are: chicken tenders, French fries, pizza. This was immediately sirens for me because I’m a believer in the importance of a healthy and well-balanced diet, specially for children and had many conversations with him about it. I used my own daughter as an example. I’m in the military and was away from her for 2 years between ages 3-5. When I received her back at age 5.5, she had also become very picky and I made it a priority to fix that bad habit. It took about 6 months and I had to ease her into it but she now readily eats just about anything and is willing to try anything. Im originally from a different country so we visit my country and travel regularly to explore other countries so that is another reason having a child that is easy going with food is important to me.
All of that to say that this has been a regular conversation between my fiancé and I and I have shared the tips that worked for me countless times. Bringing it all back to last night. We went to eat Chinese food and ordered several plates. His daughter tried two miniscule bites of new foods (pot stickers and tso’s chicken), made faces at both and had chicken fried rice for dinner. She ate all her chicken and picked at the grains of rice to avoid eating any carrots or green beans. Her dad didn’t say much other than suggested she try to eat some vegetables, to which she simply refused to and he didn’t push the issue. He told her no dessert if she didn’t try to eat her vegetables and when her fortune cookie came, he didn’t stop her from eating it or taking her lollipop home.
It was frustrating to say the least to watch him not address what she was doing and at least require her to eat some of her vegetables.
Last night it all got to me and this morning when we talked about it, I told him that his lack of serious effort in trying to modify and improve his daughters eating habits are a deal breaker for me and I would not be willing to combine our households until he made significant progress on it. He was obviously upset about this and says I’m being unfair and not giving him enough time but I see almost no effort in his parenting techniques/strategies since the 6 months he’s had his daughter half time. I know this might seem like such a trivial thing to break things off for but I could write almost the exact same post about his daughter’s education (this is her second year in 2nd grade, she got held back due to not being able to read and she’s still reading on a 1st grade level) and his lack of effort in prioritizing and making significant progress in that as well. Once again, I also have experience in this topic.
When I received my daughter, she was also significantly behind on learning to read, scoring so low on her state reading tests in Kindergarten and 1st that she qualified for free books programs. I had to turn that around as well. She now reads 2 grade levels above and is a complete bookworm. I’m genuinely starting to feel that this man is simply expecting to have me take over all the “hard” parts of parenting and he’s just waiting out until then and it’s really starting to frustrate me. My fiancé keeps saying he’ll back me up on anything I want to enforce, once we move in together. But I see this turning into a situation where I become the evil stepmother who suddenly changes everything, enforces new rules and his daughter quickly resents me. I have NO ISSUES with his daughter, in fact, children are completely innocent in situations like this. This is a complete incompatibility in parenting beliefs and its causing me to have serious doubts and apprehension in combining our families.
So AITA for delaying or even breaking off our engagement over this?
EDIT: A lot of people are telling me I’m a wicked stepmother already, but I haven’t done or enforced anything on his daughter. I know it is not my place and I, of course, don’t want her to hate me for it when we are still establishing trust. These are solely conversations between him and I and my inner concerns. His daughter and I adore each other, and her mom is supportive of our growing relationship, even offering fiance and I to have her for Thanksgiving and Christmas this year.