On the average around 3% of the people you meet are duals of your opposite gender (assuming here you are heterosexual).
If we assume that roughly 1/4th of those are single then around 0,5%-1% of the people you meet are single, opposite gender and your duals.
So if you meet one new person every day then you will meet around three potential candidates a year. If you meet one new person every month then you will meet potential candidate once every ten years. If you meet one new person once a year then you are lucky to find one potential candidate in your lifetime. So the more you meet new people the more likely you will find what you are looking for