ירא שמים האט געשריבן:כוואלט דיר גערן געהאלפן אויף אנדערע אופנים אבער פארוואס ליפערסטו אריבער אונזערע וועש פאר די בהמות און מנוולים אינ'ם טמא'נעם אינואווערזיטעט נאך דאס פעלט אונז אויס אז די חברה זאלן אנהייבן אריינצורעדן אין אונזערע הייראטן ומה לו לקדושה אצל הטומאה , ובכן מי שחס על קדושת מחנינו ועל קדושת ישראל זאל נישט מאכן דעם סערוועי ישר ככחם.
Now, to elaborate further, it is probably not true that arranged vs non arranged is the primary reason for why one group will have happier or less happier marriages. It may be a factor but certainly not the only one and probably not the most important one. I do think, that one's attachment style (secure vs insecure) is probably much more important. However, the importance of one's attachment would probably depend on how much someone expects of their marriage. For example, lets say you are having a hard time deciding which job position to pursue, or which kollel to attend, or dealing with past emotional pain, if you expect your wife to be the primary person with whom you would like to discuss these issues then it becomes important that you have a healthy attachment style. However, if you will likely ask your friend, rebbe, rosh yeshiva, mekubal..., and not your wife, then it is less important that you have a healthy attachment style.
Another example, lets say you would like to visit museums on your Sunday off, like to travel a lot, enjoy music and art, etc and you expect to do these activities with your spouse then you have high expectations and will therefore need a healthy attachment style or the marriage will suffer. Conversely, if your marriage is more about raising children together and most of your free time you have a chavrusa and you are invloved in your chasidius etc and you do not expect your spouse to be part of all your activities then your expectation is low. Therefore, it may not be so important to have a healthy attachment style. You can see that as your expectation rises so does the importance of a healthy attachment style.
That's my study.