I guess you could say ¨neither¨ or ¨both.¨ We often say ¨relationships are a two-way street.¨ Assigning fault in a case like this really is not helpful.
The only helpful thing is for each person to look at their own part of the responsibility and learn from it for their next relationship. To find a good relationship, they are going to need to understand their own expectations and try to look at whether they are asking for more than they are giving. They may be able to find a partner whose expectations are more similar to their own-- or they might have to work on changing because currently there are a number of people who never are able to have good relationships.
We all have a ¨comfort zone¨ in relationships. On one end of the spectrum, a partner feels abandonment fear when the relationship does not feel close enough. On the other end, a partner feels fear of being controlled and not allowed to be themselves when the relationship feels stifling. People often have to consciously work to expand their comfort zones and make their relationships work. Some people are just too different and would be better off with a partner whose comfort zone for intimacy is more like theirs.
I agree that personalities usually do not change too much or too easily. That is why people need to learn to understand their own personality. If it is a healthy personality, the person should be able to find someone compatible, although it may be after some failed relationships. There are some personalities that really can´t make hardly any partners happy though. It does not mean they do not love, but their capacity to identify and meet other people´s needs can be very limited.
I frequently work with people such as the women in your example if the woman comes to realize that her behavior is harmful to the relationship and that she is going to lose him if she does not learn that deal with her own feelings of abandonment. Some women can get to the point that they realize ¨I feel like you don´t love me¨ is really ¨I am feeling the fear of abandonment and am not getting the reassurance I want.¨ Some can work on their abandonment issues if they do not just blame their partner. However, if she maintains the position that the problem is that ¨you do not love me¨ she will tend to see herself as a victim. It make take several relaitonships with this pattern, if ever, for her to accept that maybe she needs to work on her own issues, and yes, sometimes either or both parties just talk a good game and really do not change.