The key word in the OP is “work.” Lots of work.
Anytime a couple comes together, they bring their personalities and backgrounds to the table. They have to learn how to WORK together, to meld their personalities and become ONE after they are married.
This is easier when personalities are compatible. It becomes more difficult when personalities are contrasting. But it is possible, and often these “mixed personality relationships” can be rich and exciting and very fulfilling for both partners.
When two people have contrasting personalities, they can each help each other bring out the best characteristics of their personalities, and suppress or eliminate the undesirable characteristics. (In other words, Christian couples can help each other become more like Jesus and “get to heaven!”)
E.g., an opinionated person can be a passionate reformer, which is good. But they can also be an obnoxious loudmouth, which is bad!
But both people must be willing to allow the other person to enter into their personality and work with them. If one or both of them shuts the other out and refuses to make any changes or concessions, then the relationship is doomed.
I’m not talking about “losing a personality”–that would be a bad thing. I’m talking about losing personalitiy traits that are not desirable or that are actually sinful, and keeping personality traits that are endearing and good.
It is often difficult to open up and allow someone else into your deepest personality. All too often, couples stay on a “surface” while they are dating, and “hide” personality traits from each other. They behave like “pals” instead of a romantic couple, and everyone, including them, thinks they are getting along great.
Then they get married, and because of the nature of marriage, they become more intimate not just sexually but in their daily lives. They open doors to “rooms” in their personality that the other partner never knew existed. Often, these rooms contain things that the other partner finds repulsive or frightening or just unpleasant.
Even then, everything can be worked out, but again, it takes a lot of WORK, and many couples are unwilling to work so hard to clean out those rooms and re-do them into pleasant rooms. Many couples split up at this point.
The best thing for a dating couple to do is open the doors and let the other person SEE their hidden rooms and decide whether or not they can live with what is inside those rooms. Start the “cleaning out” of the personality rooms BEFORE the marriage. Don’t hide from each other.
I think that Catholics and other Christians especially are more prone to “hide” before marriage as they attempt to be modest with each other. Again, I’m not talking about sex here, I’m talking about personality. Before marriage, a couple should strive for “personality intimacy”–they should practice honesty and learn as much as possible about each other. They shouldn’t date under a polite veneer of good manners and light conversation. They should duke it out verbally and learn the “secrets” that the other person is trying to hide. They should begin working together BEFORE marriage on melding the personalities. If they can’t do it, better to find out before a wedding than after.
In the case of the person who is the only child, my biggest worry is whether this person can break away totally from childhood and their parents. It is a bad thing for a woman to find herself chained to a “Mama’s Boy.” Often, women who get trapped in this situation do become “opinionated”, because they are trying desperately to make their partner grow a spine and break away. I would tell any woman who is involved with a potential Mama’s Boy to break it off–it’s very difficult and will make your life a hell on earth.
