One must be a little bit careful with this expression.
"für meinen Freund" means "for my boyfriend in most of the cases, but sometimes it also means "for a friend of mine" (as in the example).
If you really want to express "for a friend of mine" you can say "für einen Freund von mir", this clearly means that he is just a friend without generating any misunderstanding.

@el-vecino Das stimmt ja schon,aber wo sind denn die Anglizismen wenn man sie braucht. Hier sind Google-treffer in Bezug auf "für meinen boyfriend" :)

@Dejo: Es gibt noch eine andere Möglichkeit, ohne Anglizismen zu nutzen. Man kann auch "für meinen festen Freund" sagen.
(There is another possibility without using English words. You can say "für meinen festen Freund", this expression always means boyfriend)

@ el_vecino >If you really want to express "for a friend of mine" you can say "für einen Freund von mir"...<

Das kann man sagen, aber meist sagt man einfach und unmissverständlich "für einen Freund" ("einen" instead of "meinen" - this makes it clear that this friend isn't the boyfriend. But at the same time, we have to know that "mein Freund" isn't necessarily "my boyfriend".)

It wasn't my intention to start a debate about the differences between "mein Freund", "ein Freund", "mein fester Freund", etc.
I just wanted to say, what people could understand if you say that sentence, specially in the german sentence which is a little bit ambiguous, and give some alternatives if people want to give a more specific message. If they want to use it, it depends on them.
@arcticmonkey: I agree with you, it's not the best solution.
@al_ex_an_der: You are absolutely right.

Sometimes it isn't easy to translate sentences since those here don't have any context, each language is different and words don't always have the same meaning, sometimes it depends on the intonation or how you say it and sometimes also on the actual message you want to transmit.
The fact is that the sentences in the other languages aren't as ambiguous as the german one.

So, in most of the cases:
my friend (a friend of mine) = ein Freund, ein Freund von mir, mein Freund, mi amigo, mon ami, il mio amico.

my boyfriend (in a relationship) = mein Freund, mein fester Freund, mi novio, mon petit ami, il mio ragazzo.

I'm very appreciative of the fact that we had this discussion. It explains why I got sideways glances when I mentioned "mein Freund" LOL I came to the conclusion, perhaps erroneously, that Germans don't have friends ...they only have Kumpels and Kollegen :) But I find Alexander's solution ingenious, "ein Freund" instead of "mein Freund".