I miss you. Miss you a lot.

In our culture the sentences like "I miss you." or "Miss you a lot." are usually used between family members or same-sex friends. If a female says or wites "I miss you" to a male friend, it would be considered there is a sort of girlfriend-boyfriend relationship between them. What is the situation in English? If a Chinese girl writes "Miss you a lot" (in English) to, say, an English male friend (not her boyfriend), would a native English speaker think that she is writing to her boyfriend? Or would the English male friend think, "What? Does she consider me her boyfriend now?"

Dear native speakers, please explain.

An Asian.