I know it is hard to hear, but some people are going to have a hard time understanding. The cold hard truth is that having a disease like Crohn's, or an ostomy or any other real life problem is too much for some shallow people to handle.
The good news is that it really helps you weed out the people who aren't worth your time any way. In my experience, the people who leave are the ones who would were not worth my time to begin with, leaving me with the best friends and the best husband possible. It took me a long time to find him, but it was sooo worth it.
My husband was never bothered by my Crohn's even though it meant that he had to deal with all of my embarrassing poo issues, pain, sadness and hospital visits right from the beginning of our relationship. When I had my ostomy, he actually loved it because I was able to do so much more than when I didn't. In fact, I think he really would rather I still had it and was able to go out and have fun as much as I did when I still had my bag. Also, he never saw me as any less beautiful or sexy. Some of the best intamate times we ever had were when I had the bag, no lie. There are lots of sexy ways to cover it. Fell free to PM me if you want ideas.
No matter who we are, everyone is going to go through things in their lives, be it an ostomy, Cancer, depression or a death in the family. When these things happen, sometimes the people who we thought would be there for us forever show their true colors and bail. I really believe that in a way, people like us who can not hide all of our problems and have to be who we are from the start scars and all, have a gift because we get to find out right away who the worth while people are and who the temporary people are.
My husband and I got married in July with my ostomy and it was the best day of our lives. It would never have been so perfect without that bag. Even when I had a leak later that night while we were out to eat, it didn't really bother me because I knew it didn't bother my husband (still love calling him that!) one little bit.
My advice is to be as honest as you feel comfortable being right from the start. If you act embarrassed, it makes it an uncomfortable situation for the other person. If you act normal, they will think it is normal. This lesson was a hard one for me to learn, but it helped me so much in my life. I am never ashamed to tell people about my disease or show them my scars. When I had my ostomy, i let everyone know. I figured that they all knew something was wrong anyway when I went in for surgery. Why let their minds run wild? No one treated me any differently.
Dating is hard enough without an ostomy and I'm sorry that you have to go through this. I hope you meet someone wonderful soon who makes all of your dreams come true. Just know that you are not alone. There are plenty of people on this forum who are dealing with exactly what you are right now.