I can't speak for Clemson, but the above descriptions hit eerily close to home. Would you please expand on your line of thinking ... you very much have my attention.
I do not wish to threadjack but I do believe that this information would be relevant to the OP.
Adult relationships are very complex and involve an intricate network of thoughts, feelings, perceptions and responses. Due to this complexity, an immature individual is ill equipped to fully understand, act and react in a way that is productive and beneficial to the marriage. They are also incapable of handling their own emotions and feelings which further disadvantages their position.
Since their mind does not process information fully, or in some cases barely, their words, actions and interactions will paint a true picture of who they are. What may be superficially perceived as a person "acting cute" may, in reality, not be an act but rather an indication of their inability to handle or cope with a particular situation.
Likewise, displays of anger can be an indicator of a seriously underdeveloped intellect. In a truly mature individual there is rarely a need to display anger but in an immature person anger is quite often the first response to an adverse situation. Whereas a mature individual could communicate their concerns by presenting a reasoned argument, an immature person would become angry and storm off. Therefore, how a person handles their own emotions and feelings can be indicative as to their level of maturity.
When dating, there are usually behaviors displayed that will indicate a persons level of maturity such as the fiance in this thread becoming obsessed with the OP, unfortunately most times they are either overlooked in the infatuation of dating or taken as "cute" and therefore dismissed.