Harlen sits next to 3 phonetic neighbors — Harlan, Harley, and Darlen are the closest matches by sound. Most share Harlen's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"rocky land, gray land"
"son of a nobleman (variant interpretation)"
"of the birds, bird-like"
"brave one, bold and courageous"
"little seal"
"God is brother"
"modern invented name with noble, airy connotations"
"son of Brice; son of Bryce"
"son of Lars (son of Lawrence)"
"the Christian cross"
"one who loves God"
"peace and agreement"
"wise one, seer"
"star"
"highlands, uplands"
"friend to everyone, ally to all"
"may God protect"
"little red-haired one"
"roe deer forest, deer wood"
"wolf-desire, wolf's help"
"lord, master"
Similar sound: These names share phonetic patterns with Harlen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English har + land origins, giving them the same cultural heritage as Harlen.
Rhythm: Harlen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.