Struggling to Move Past My Partner’s Reaction to a Past Situation—Need Advice

[Tybruh]

I’m a 19-year-old guy, and my girlfriend (also 19) and I have been together for over a year. Early in our relationship (around 4 months in), she shed a few tears when a former friend (who she had a purely sexual relationship with in the past) joined the Navy. She’s explained that her reaction wasn’t about him personally but about the danger of the situation, and she’s cried over other friends in similar circumstances.
To her credit, she cut him off early in the relationship out of respect for me, and she’s been consistent in showing her commitment to us. Despite this, I can’t seem to stop fixating on this moment. It makes me feel insecure, like I’m not enough for her, even though her actions have shown otherwise.
I trust her explanation, and I want to move forward, but this situation keeps replaying in my head and causing anxiety. Has anyone been through something like this? How can I let go of this and rebuild my confidence? Any advice would really help.

nobody can give you the reassurance you’re looking for with any certainty.
If she also reacts the same way regarding other people, rather than it just being him, it’s likely that there’s nothing for you to be concerned about.

When I was your age and in my 20s, people used to tell me I took things too seriously, too much to heart to a degree that was a problem and they were right. It took me ages to work out that there was no magic wand: I just had to take things less seriously. And realising that made me able to do it.

You’ve got into a cycle of obsessing about this, focussing on it and winding yourself up about it. I know that feeling. It’s a bit like pressing a bruise. And there is a perverse, uncomfortable kind of pleasure to it. There’s also a hyper-vigilance about this. Being in love, in a happy, mutually respectful relationship is amazing. It provides huge joy and contentment. The flipside is that you probably feel a bit vulnerable because you know it would be painful and sad (at least for a while) if your relationship were to end. This is a risk everyone takes when they embark on a relationship. But the rewards are worth the risk, even if a relationship ends. I’ve had my heart broken a couple of times in the long distant past. But my heart mended itself after a while and it didn’t take away from the fact that both relationships were significant, joyful, nurturing and sustaining while they lasted and I learnt a great deal from them. For decades, those relationships have just been a lovely part of my personal history that I smile to remember.

So your recurring thoughts are you pricking yourself with your sense of vulnerability.

But you can beat it. There’s no magic wand here but ultimately these are your thoughts and you control how seriously you take them. They are just thoughts. You don’t have to engage. You can let them float past like balloons. You need to re-wire your brain a bit. Once you change how you respond to these thoughts, you’ll have them less and less. If you indulge in them, you risk spoiling a happy, healthy relationship; you risk ruining what could have been great. In fact, the surest way to ruin this joyful relationship is to focus on these thoughts rather than letting them
go.

She cut him off, just because you told her to? But you still "can't get past it"? You cannot control someone to this degree.

She's only young, I would be advising her to be wary here.