This is really a profound question on your ability to get
hitched in a healthy, romantic relationship.
First thing first. What is the level of relationship you are
talking about? Most teenagers today are confused on the level of
relationship they have with the opposite sex depending on the
scenario they are in. One scenario would be love at first sight.
Another would be childhood friend or through befriending in a
social setting. It makes difference in the process of a
relationship.
Next, your ex alleges that she left you due to your immaturity. How
about this then: older women, especially celebrities, go after
younger men? Duh. What is your ex thinking? More like she is the
one who is immature. However, there must be a reason if every ex
told you the same thing and this requires you to assess your
goodself. Ask this question: Who am I?
Having more than one ex has its own implication. Just like there is
yin and yang, black and white, good and bad.... Some may perceive
you as playboy, some may perceive you as not-the-husband material.
As rightly pointed out, not everyone could not find Mr or Ms Right
on the first try.
My conclusion is that both of you have a conflicting expectation of
what is an ideal couple. A relationship is in a fact a delicate
process that many do not pay attention to small details. Better
focus on the education first if you are under 21 years old.