Help in a translation

[Galin]

Maybe...

*i elen olorion 'the star of dreams' (plural olori is from text in Unfinished Tales, said to arise from older olozi 'dreams, visions')

*siluva (no long vowel) 'will shine' (attested in nai elen siluva lyenna on a card signed and inscribed in Quenya by Tolkien)

*hendunyanta 'into my (two) eyes' (this dual allative is a guess; though eyes are a natural pair of course, and I think the allative case is the way to go here).

My girlfriend would like to have an elvish phrase as a tattoo, so we must be as sure as possible of its correct translation.

That's good (especially since tattoos don't erase easily) and thus I'm going to say that you should actually disregard my attempt here at Neo-Quenya. To be 'as sure as possible' (which again is a good thing), and for actual Quenya, I say look for something in the books, Tolkien-written, and copy it... even better if it's already in Elvish characters (assuming you want something in Elvish writing).

I won't go into my usual annoying rant on Neo-elvish versus actual Elvish, but maybe you can go to...

http://www.elvish.org/

... and read the FAQ.

I wouldn't put my own suggestion on my arm for a tattoo even if some of the top Tolkien linguists out there agreed with it (for reasons the FAQ explains well enough). I suggest you also read Elvish as She Is Spoke under the link 'Articles' if you have the time and interest. Again, despite that I took a shot at it here, I think one should only use Tolkien-made Elvish for tattoos. Also keep in mind I'm just some person on the web (though interested in the languages), and no expert.

OK, have I 'warned' you enough

It's up to you of course. I wouldn't be hasty in any case.