Translation:My boyfriend is not romantic.
I wonder if there is a good way to figure out the meaning of compound Chinese words?
For example: 浪漫 means romantic. 浪 alone means wave; breaker; unrestrained; dissipated. And 漫 alone means free; unrestrained; to inundate.
Are the Chinese who know just 浪 or 漫 individually able to deduce the meaning of them together?
Just a thought. Maybe someone can answer.
It's often possible to get some information on the meaning of a compound word from the component characters, but it might not be enough to fully specify the compound word's meaning. There are also many compound words where the component words don't provide semantic clues. A few illustrative examples:
电脑 means "computer; 电 means "electric(ity)", 脑 means "brain" --> knowing only the component characters, you can probably fully piece together the exact meaning of the compound word
小时 means "hour"; 小 means "small", 时 means "time" --> knowing only the component characters, you can deduce something about the meaning of the compound word, but not necessarily the exact meaning
马上 means "immediately"; 马 means "horse", 上 means "up" or "on" --> knowing only the component characters doesn't really help with the compound word
浪漫 is interesting because it's actually an example of both cases 1 and 3. It originally meant "unrestrained" or "indulgent", used more in literary contexts than in spoken contexts. 浪 normally means "wave" as in ocean wave, but it has a less common definition of "unrestrained" as in not being bound by morals. 漫 most commonly means "overflowing", but it has another definition of "unrestrained" as in free to spread. Clearly in this case, someone who knows the definitions of the individual characters could easily deduce the meaning of the compound word.
However, at some point, 浪漫 began to be used to mean romantic through photo-semantic matching with the English word "romantic". I.e. a native word that sounds similar to the foreign word and has a somewhat related meaning came to be used to take on the foreign word's meaning. With this modern definition, knowing the meanings of the component characters doesn't really help to deduce the compound word's meaning.
I agree with the last part of your explanation. Most Chinese people take this word as a pure transliteration of “romance, romantic” (alternatively “罗曼, 罗曼蒂克”), or they only know these meanings but the original ones. I think historically there must be some great writers proposing 浪漫 as a better translation even though it does not originally mean “romantic”.