It's called being stupidly sentimental. There's no industry term for it. But it is a problem and you're right that you need to address it if it's happening to you. Very few people write with gold ink upon heavenly parchment and can send that off to the printer.
There's this thing called revision. There's this other thing called editing.
At least 50% of the work in writing is knowing how to throw out, alter or change what you've written for better effect. So first, recognize you're actually bad at writing some things. Second, learn that it's ok to change those things. And third, change those things and get better at recognizing when and how to do this.
There's no real question here. You already know the answer. But if it makes you feel better, sure you're not alone. I do it to.
Validation.give(); But, if you're just here for sympathy you won't ever really be the kind of writer who finishes quality works. You can stop reading now if you like, the rest of this is going to be how I dealt with it and may not be relevant to you.
There are lots reasons you might be attached to anything you've written. The secret is to figure out why you are attached and address that. It's usually a personal issue that resonates throughout your life in otherways; at least it was for me. I used to write slow. And even now that I write faster I don't have a lot of time for it. Therefor every word I write is valuable. Because it's a moment I wasn't spending with my family. It's a moment I wasn't making money. It's a moment I can't get back. This is the thing I had to conquer. Changing things is hard and expensive and I've already put in so much work. For me I needed to change my expectations and my writing method. I've moved on to snowflake which allows me to make changes earlier on grander scales so I don't get to the point that I've got a finished piece of work that is actually garbage.
There are other variations on this. The most prevalent one is likely this one. Where you've thought about something long enough that it's crystallized in your head and you yourself can't see a way to change. Everything is justified in your mind; but often that justification isn't on the page. Your readers don't get it and they are telling you this. This is where the advice comes from to take your work, stick it in a drawer for a few months/years and come back to it later. Work on something else (but try and learn from what you're hearing or you'll just repeat your mistakes). When you come back, a lot of your love and familiarity will be gone. You'll be able to work more objectively.
Some reading that might help, there's no real theme here other than this is a common problem across everything: