Psychology in my opinion is (just like any other science) a science based on loads of observations, which have eventually been formed to create some framework or model that seems to fit real life, but still always evolving.
Loads of very observant people had loads of overlapping and non overlapping observations, and opinions.
There is absolutely no one to tell, if what we think is going on "in someone", is really what is going on.
Observations and our instinct are all there is to create the model, that makes us think that we understand the "problems" more. (they are not problems)
You could take any famous characters of psychology (e.g.. Sigmund Freud), who has surely contributed a lot to science, so we think we understand more how our psyche works, but for sure no one will ever know.
All we know is the model we apply to understand people, seem to work for a mass of people, but it will never work for everyone every-time.
I believe it is false to say that:
"You'll find that whatever issues you're having in your relationships now, you'll find persist across all your relationships, despite your partner, so do your best to make the one you have work"
People are all sorts.
People change by self observation, and change even more by observing others.
If they ever notice despite how different we are, how much the "same" we all are at the same time. If they ever notice, that our "so unique" ways of behaving and living life have such a strong template like nature.
Some people will surely suffer from what the above statement says.
Some will not, because the more intelligent and openhearted someone becomes with time, the more wisdom it will develop inside.
The more wise someone becomes, the more it will understand about him or herself, the more it will accept him or herself.
That is all that matters, not to go against of who we are.
We do that by slowly learning what the "Baggage" means in our case (this time around, in this life of ours).
From that era in ones life, life can be like anything, even very different from what it has been before.
When one comes to embrace the true self, how ever (f..d up) it may have seemed before (when we still thought the "Baggage" was part of the definition of the self),
that "newborn" will have a different presence, it will attract a very different audience.
That "new shape" of attraction is what will define our later relationships.
So to say that:
"I am curious if there is any validity to my professors statement..."
I am not sure you'll ever truly find any validity... it is surely valid from your professors point of view, but does it have to be valid from your point of view???
You surely cannot expect someone else to tell you whether your professors opinion should be your opinion too?
Few lines above I was saying the opposite of your professors opinion, because that is what I think of life.
Both yours professors and my contributions (and even Sigmund Freud's), are at the and of the day just opinions, based on how we individually perceive life (including others').
The only thing that matters is how YOU perceive life, and perceiving others living their life.
If your perception of life (relationships, ....) is not good enough according to someone at University, or wherever you get in life, that is not your problem.
Referring to your relationships, that is all there is to you first hand, so how could you not look at life generally through those experiences?
(again this is my opinion)
If you are curious enough to keep digging and thinking about what recurring problems you have had in any of your relationships, then once you may compile a short list of these things.
You may find, that no matter how many types of conflicts, misalignment you have ever had
with your partners, they will always be about 1 or 2 MAJOR things in life.
Any of the conflicts, or what ever you don't like about others or yourself, you'll be able to break down into very basic personal feature of YOURS. The "problem" (it is not really a problem, rather cause in you) is usually so simple you don't even suspect it to cause certain things.
All those problems will come down to 1 or 2 of basic things, like low self-esteem is one of the most common one.
I am sure it is obvious to you, that whatever it is, it is part of your "Baggage"...
The fact that you are still experiencing those recurring problems means you haven't adequately figured out your baggage, and THERE IS NOTHING WRONG WITH THAT.
Life is giving these opportunities and time to you to find the answer, and then once you know what it is, to make friends with it.
The rest of your life is still ahead of you to achieve that, it may or may not take that long.
At the end of the day, I believe we are here on Planet Earth to watch the "show".
Whenever we see something we need to react to, we do so, because it is in our nature, whether we want to react or not.
We cannot "screw up"... we just live life, and get experienced that way.
Or if we become numb and indecisive, then life will live us, and get experienced that way. (it gets rather bitter that way...)
Either way we get what we are here for, even if we forgot what we came here for.
I am sorry, this turned into a "What are we here for???".
I shut up now.
I wish you the best...
(the easiest is often not be the best, just listen to your heart)