It may not end, but it has been dealt a fatal blow and WILL die at some point.
Trust and honesty go hand-in-hand. WE must be able to trust, and our actions must also be trustworthy. And we must be honest with ourselves if we are going to be able to be honest with another. And if we are not honest, there will be no trust.
Trust and honesty are 65% of what makes a relationship last, and without it the relationship is doomed.
As for fighting, it is normal, but dysfunctional.
We fight because WE cannot face and deal with our pain, so we get angry and then we try to make our partner change .. so WE don't have to work with OUR emotions.
But when we fight, our partner feels unloved, and they feel like they need to stand up for themselves.
ALL relationships have SOME fighting once the infatuation dies out. But it should never be too much fighting because every negative in a relationship needs FIVE positives just to balance out the negative.
And the fighting should NOT start until the couple has been together for a year of more. The sooner it starts, he more fighting there WILL be later on.
Couples who have successful marriages take 20 years of working on their own emotions before they can just relax and accept each other.
Yes, it hurts. Relationships DO hurt. And it is up to US to learn to deal with our emotions, to relax and accept them .. so we CAN accept our partner.
Not every partner IS acceptable, and we all vary in how well we can work with our own emotions.
But fighting always means we are NOT working with our emotions, but are trying to make our partner responsible for OUR emotional reactions.
As for truly loving .. you are mistaking attachment for love. Love is NOT a feeling. Attachment is a focus on how WE feel . .it is selfish. and love is NOT about selfishness.
Love is a choice, and it is the choice to accept and nurture our partner. Anger and fighting are signs of NOT loving the other.
And being "sorry" does not undo the damage. TRULY being sorry means changing how we behave. It is not words, and not ever tears of regret. It is change.
If you are depressed with her, then you are NOT lucky to have her. You are unlucky. Stop lying to yourself. Either this person is wrong for you, or you are not ready to make a relationship with anyone last .. or both.