"It would be very nice of you if you can correct mistakes in my writing. Thanks"

Anyway, I wasn't being pretentious. and I was just worried with about him.   and helped him with everything With all my heart, I would help him all that I can. One day, things had changed. Probably it is because we went off to different universities, we could and barely keep kept in touch. I felt like we gradually started to grow apart. We won't be Unable to see each other so often and share common interests, we gradually drifted/grew apart. That had This is to be expected. I was not too concerned and we just lived continue with our lives as we would occasionally checked in with on each other.

"It would be very nice of you if you can1 correct mistakes in my writing. Thanks."

1 I like to use present tense.  This is more proactive and assertive.  Using, "would", "could" is more polite but to me, namby-pamby.  The first part "It would be very nice of you", is already very polite.

"It would be very nice of you if you could/또는/would correct any mistakes in my writing. Thanks"

I helped him all  (that) I could.

However, one day, things had changed.

It was probably because we went off to different universities, and we could barely kept in touch.

I felt like we gradually started to grow apart.< 좋습니다.

We weren't able be able to see each other as/very often and do things together.

That had to be expected.

I wasn't)=was not) too concerned and we just lived as we occasionally checked in with each other. < 좋다.

"It would be very nice of you if you could/would correct mistakes in my writing. Thanks."