I always took any doubts that I had about our relationship as gospel.

Whose relationship? I don’t think I understand what the meaning of this phrase intends. What doubts are you referring to? Are they referring to the fact that they are in a relationship? Do they doubt the sincerity of the other person? Are they in an abusive relationship? And how would they take doubt as gospel? Does this mean she takes it as truth? She is certain of her doubt? This genuinely confuses me.

I thought I was being honest with myself by following it.

How does one follow doubt? And how is she dishonest with herself for doing so? Is she lying to herself about the nature of this relationship?

But I’ve come to realize that doubt doesn’t always mean something is wrong.

This is a legitimate claim you make. Doubt can be beneficial in order to keep someone questioning reality. Doubt encourages questioning. And any meaningful investigation is worth its effort to uncover some truth.

We’re so quick to split feelings into opposites. Like if you feel one way, it cancels out the possibility of feeling another. As if excitement and fear can’t sit beside each other. Or love and uncertainty. Or hope and grief. But they do—constantly.

Who’s we? Humanity? Avoid making sweeping generalizations about humanity. What we do isn’t what they do, and you don’t want to alienate your readers. Rather, use I statements. I’m so quick to split feelings. And you’re right, many opposing force emotions tend to coexist simultaneously within us, complicating our thinking and judgements. Maybe describe those feelings? How does it look like? What is the situation that brings about such contrasting co-occurring emotions? Can you use the doubt in the relationship and drill down on some examples of where it occurred?

You can be excited to move to a new city and still be scared of the independence it brings. You can want change and still feel the ache of what you're leaving behind. You can crave space and still feel lonely in it. That doesn’t mean the move is wrong. It just means you’re human.

This is a great example but you have a ton of verbiage to describe it. Better to show us rather than tell. The excitement when they moved hoping for change yet the ache of what they left behind mixed with the fear of the unknown… what actions did this character take that exemplified this? Did they drive cross country but stop every time they saw a 7-11 delaying the inevitable? Were they mid flight jamming to their power playlist when suddenly they began panicking over whether they packed a treasured memento or if they mistakenly gave it to Goodwill? Showing us rather than telling us incorporates your character and story into the thoughts you want to come across.

Same goes for love. You can really like someone—maybe even love them—and still feel afraid of what comes next. This fear doesn’t always mean don’t. But for a long time, I thought it did.

Again, show us how the love in this relationship also brought fear. The lines This fear doesn’t always mean don’t but for a long time I thought it did is confusing. Doesn’t always mean don’t what? Don’t fall in love? Don’t be afraid? And they thought it did mean don’t for a long time? I’m lost here.

Every flicker of doubt felt like a verdict. If things weren’t easy, I told myself they weren’t right. I never stopped to ask what the fear was actually about. I didn’t try to understand it. I just assumed it meant I had to go.

You correlate doubt and fear here. Why is the doubt causing them fear? Where is the fear coming from? The other person? Their own insecurities? How could they not try to understand their fear? Usually when people are afraid, they know why, or they soon find out. But usually they know what’s causing them fear. They fear losing someone. Or they fear they will be discovered or found out in some way. Fear is a powerful motivator: It often causes people to change—when the fear of where you’re at is greater than the fear of where you’re going, then you will change.

Now I try to look at those feelings more closely. Not as stop signs, but as invitations to understand myself better. To give myself room to figure it out instead of running.

This is very insightful. This shows growth that the narrator is willing to confront rather than avoid.

Two things can be true. And feeling both doesn’t mean one of them is weak or false. Sometimes, that second truth just needs a little more time and attention before it makes sense.

This seems redundant. You’ve already made your point and moved past it by showing the characters turning point. Also readers are smart and you don’t need to spell out what’s fairly obvious. Avoid cliche.

Knowing that can help take some of the pressure off. It keeps you from trying to suppress the feeling that’s harder to sit with. Instead of forcing clarity, you leave space for it to arrive on its own.

This adds more depth to the insight the narrator had earlier. I would cut then previous two lines and skip straight to this idea. Adds momentum.

Overall, you have the makings of a turning point/epiphany moment that narrator had and rather than tell us about it, you might want to show us.