Prepositions are tricky to figure out. I'd like to know whether or not I can use these two prepositions interchangeably in the following examples.
It's very important for me/to me to study abroad.
For me/to me all that matters is how much it will cost.
You are the most beautiful girl, at least for me/to me.
Living in our house is just unbearable for me/to me.
As an ELL, I have to make sentences in a way like assemblying parts. At times, the contrived sentences may seem to be a little bit unnatural to native speakers, so the examples above are just tokens here. There must be better ways to convey the meaning.
Best Answer
Let's tackle these one by one:
Here both can be used, but they would have slightly different meanings:
To better understand the difference, let's add "My dad thinks":
...means he thinks it'll be a good thing for me.
...means he thinks I care about studying abroad.
Secondly, technically the same rule as above also applies here: "to me" means directly to you, "for me" might mean that others are the ones who care, though in this case this difference is very small, and somehow the "for me" sounds a tiny bit worse or more awkward. So:
= eg. I don't care about the time it'll take, I just care about the price.
In the second version, let's add on a beginning:
Here - and this is a reach - but it could technically be understood to mean that my mother thinks this girl is the prettiest I can find, though there are prettier ones out there in general
I imagine some might use such a sentence as a concatenation of two ideas: "you are the most beautiful girl" and "you are the girl for me", but technically this would not be correct.
On the other hand, in this sentence:
...the better option would probably be the first one, but again, there would be a slight change in meaning:
"...for me" would mean that I'm acknowledging that while others may also have (near)perfect girlfriends, my specific needs, character, interests, etc. mean that you are the one who is perfect for me. However, note that the girlfriend would prefer to hear this as "You are the perfect girlfriend for me"
"...to me" could be understood to mean something along the lines of, You weren't (or aren't...) the best girlfriend for your other boyfriends, but I think you're perfect. That said, in this case you can't skip the "at least" - it wouldn't sound good without those two words.
To summarize, no wonder you're having problems, because there's a lot of nuances! But I hope this will have helped a bit :)