Hey MGNYJCWS, welcome to the forum. I'm kind of on the opposite end of what people are saying here. Yes, it's her life and her body and all that, but a marriage is a partnership. A true partnership. I had Crohn's before my husband and I started dating, and I've been hospitalized closed to 40 times in the 6 years we've been married. We have two kids, ages 4 and 2. So I am proof that it CAN work, but also proof that Crohn's is kind of an up and down thing.
However, I agree with your concerns. I think the biggest thing that has me concerned is respect. A marriage can ONLY work with respect of two kids. Sure, it's her life and body, but you're also considering her as the mother of YOUR children, so you do have some say in it.
The only way this works is if both of you have respect for each other. What other people are saying is true - Crohn's is trick with regards to diet. Some people have different trigger foods, and most healthy foods (like fresh fruits and veggies) are extremely painful.
On the other hand, though, she needs to respect your concerns for her because of how it's going to impact your life. If you sit down to have a respectful conversation with her where you are asking her to help you understand why she eats certain foods, etc., but she doesn't respect it back, then that's a warning sign of more than just Crohn's, if that makes sense.
For example, if my husband became concerned with my stress eating chocolate (true story) because it is a trigger food for me, and I just wanted to eat chocolate because it makes me feel emotionally better, then that's wrong on my part. I'm eating something that I know is making me sick, and I am disregarding his feelings. If I'm sick, he's the one that has to pick up the slack for watching kids, taking me to the ER, etc. Now, if he starts pushing fruits and veggies on me (also trigger foods) without listening to my reasoning on why I don't eat them (they are painful, and I know from experience, and my dr has cautioned me against eating them frequently), then he's not respecting me.
I hope that makes sense. You can have disagreements about it, and in the end you can't force her, but if she doesn't treat your concerns with respect, and/or if you don't treat her reasoning with respect, then that's kind of a red flag.
"For this thing I besought the Lord thrice that it depart from me. He said, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities; I take pleasure in infirmities, reproaches, necessities, persecutions, distresses, for when I am weak, then am I strong" 2 Cor