Coidzor, if you are asking about how long after one of YOUR relationship ends, it's purely up to you. Only you can determine how long you need.

Stadge, I second Felix- listen to Pancake. From age 16-19 I was in a relationship with a Boy, who was 15-18 during the relationship and lived 1000 miles away from me. The distance didn't stop us trying, we didn't even see each other for the first year (we'd met at a Latin Convention in Texas; he lived in New Jersey, I in Florida) and only every 6 months after that.

Cheers~