I'm not sure if it is correct, but in such a case i would have used "han står mellom meg og deg" or "han står i veien for meg og deg" (lit. he stands in the way for me and you).
In both cases you have to stress "oss"/"meg og deg" to signify the relationship being an unit (of two people)
Thanks! By the way, I'm assuming you're not a native English speaker. While "unit" begins with a vowel, you do not use "an" in front of it. "Unit" is pronounced with a long "u" imitating the sound of "y", unlike "umbrella" where the "u" sounds like "uh." So while a vowel determines if you use "an" or "a", the difference between using a long or short "u" stands as an exception.
To elaborate on 'an' and 'a' in English its whether the sound is a consonant or vowell sound rather than the spelling. Technically in British English 'an historian' and 'an hotel' are both correct for example as the 'h' is silent but this pronunciation is never used in American English
Be careful not to overgeneralize a rule... Even in American English 'an' is occasionally used before the word "historic" in particular. This is especially true in academic texts, and truer still in older ones.
You're right though, it's mostly about consonant sounds vs vowel sounds. Secondarily it's used in academic circles to make things look spiffy.