Rarely if ever!
First of all people who are unhappy and dissatisfied with others (early on) are most likely not going to invest time and effort!
The start of a new relationship is generally the "infatuation phase" where both people bend over backwards to impress and please one another. If a relationship starts off "rocky" most people will automatically take that as a sign that they are with the wrong person.
Relationships are a (choice) and not an "acquired taste". If one or the other has to majorly "change" in order to make the relationship work that means they've selected the wrong mate.
There are only two ways to experience joy and peace of mind in relationships: we either get what we want or we learn to be happy with what we have. People aren't looking for others to change them!
Ultimately everyone wants to be loved and accepted for who (they) are. You're better off seeking out someone who (already is) the kind of person (you) want to be with.
The goal is to find someone who shares your same values, wants the same things that you do for the relationship, naturally agrees with you on how to obtain those things, and last but not least there is a mutual depth of love and desire for one another.
"Never love anyone who treats you like you're ordinary."
- Oscar Wilde