Most Helpful Guy
Because they either realized they made a mistake breaking up with them or miss a particular thing about them. But knowing for a fact, not all relationships turn out to be great when you re-date your past. If arguments was a big issue from the past, even if you try to work it out, possibilities it will happen again. (Had happened to me; but I'm thankful that I didn't pursue it) plus guys also realized they can find any better or just could be desperate being with someone again.