I am still happily married - so the regret is not about that.
The regret is due to the following reasons:
1. I started the company hoping that I will be able to be financially secure after a while. That did not pan out, and I am in the same state financially as I was before I started the company.
I have many other ideas too. I thought I will try out the most financially lucrative one, get enough money to be safe for the rest of the life, and then try out my other ideas. That is not going to happen anytime soon.
2. The realization that I quit on something. I did not try enough during the sales part. I could have persevered and then if I fail, I can accept. I myself know that I did not try anywhere near hard enough during the marketing/sales part.
It is very hard if you know you quit before you acted with your full energy on it. I did not do that, and so it is quite a big regret.
3. I now know that it requires perseverance. I did not know to what level - at that time. I lacked it then, and I am not sure whether I lack it even now. Unless you jump in there, you really do not know how deep you are.
So my confidence also has taken a hit.
Even though I tried a little bit, I am still in the same position as before. That does hurt, especially when you know it is only your fault.