男朋友 and 女朋友 have the same thought process as their English counterparts, as in both words are compounded of (the gender) + ("friend"), even though they're actually used to refer to a romantic partner of said gender. Are there any linguistic reasons for that? Did English and Chinese-speaking nations have any contact in the past or have these 2 isolated and totally different nations had the same logic for this word specifically?
The English words boyfriend/girlfriend are modern; their usage to refer to romantic, unmarried relations dates to around 1922. This is also where other terms like "dating" arose.
Similarly, in Chinese, 男朋友/女朋友 do not exist in pre-modern times. Other terms like 佳人 would be used.
The Republican Era saw big changes in Chinese culture and adoption of Western culture and language. It would be easy to conclude, therefore, that the words 男朋友/女朋友 were borrowed from English during this time.
I think in English we say boy/girl friend for friendship and boyfriend/girlfirend for relationship. In Chinese, the counterpart is 男性(Xing )朋友/女性(Xing )朋友 for friendship. 男朋友/女朋友 indicates relationship in general.