快速答案
在巴西的恋爱语境中，ficar 指随意、未定义的关系；namorar 指正式确立的恋爱关系。
可靠的方法是先判断这个词在句子里的功能，再翻译。
每个词的作用
ficar
to hook up or see someone casually
Use ficar for romantic or physical contact without an established committed relationship.
namorar
to date or be in a relationship
Use namorar for an ongoing romantic relationship with mutual commitment.
如何选择
- ficar: Choose ficar if the sentence points to romantic or physical contact without an established committed relationship.
- namorar: Choose namorar if the sentence points to an ongoing romantic relationship with mutual commitment.
例句
Eles ficaram na festa.
They hooked up at the party.
Eles namoram há seis meses.
They have been dating for six months.
常见误区
Ficar has many unrelated meanings. Only context with people and romance gives it this specifically Brazilian sense.
放到语境中练习
从你的真实生活中选一个句子，写两遍：一次用 ficar，一次用 namorar。如果两个版本都可以，说明意思怎样变化。