她勉強的跟他一起出去
(不是不情願,而是其他原因,例如她雖然喜歡跟他出去,但是身體不舒服)

How to express “勉強的” in English?
Are there any specific words for “勉強的”?
Thanks in advance if anyone tells me that.

unwilling勉強的

uncheerful勉強的

strained牽強附會的意思

Reluctant is another word for unwilling, it’s an adjective.
Some words meaning reluctant (all adjective):
• Averse
• Backward
• Disinclined
• Grudging
• Hesitant
• Indisposed
• Loath
• Recalcitrant
• Slow
• Unenthusiastic
• Unwilling
Some words meaning reluctance (noun):
• Aversion
• Backwardness
• Disinclination
• Dislike
• Disrelish
• Distaste
• Hesitancy
• Indisposition
• Loathing
• Repugnance
• Unwillingness

In that case, I would say:
‘She went out just for him’ or ‘she went out because of him’.

我不知道該怎麼用一個字講，我會說整個括號裡的話。頂多啦，比如大家都已經在...遊樂場好了，然後我gf是這情況，我可能會說"She dragged her butt all the way here"，當然這段話也沒能直接表達，這英文也有其它意思在，所以聽到的人會問我"Why?" "What happened?"

事實上，如果光說這句中文"她勉強的跟他一起出去"，聽到的人大半仍是認為她unwillingly(不情不願)。這中文雖然也有"不是不情願,而是其他原因,例如她雖然喜歡跟他出去,但是身體不舒服"這意思，但是也是要另外說明，這樣子聽的人才知道吧...

通常用 unwillingly，但就以你上面的句子而言。

She forced herself to go out with him.

另一例子我以前問的：
Does Jeff speak English?
我問同學，Jeff會講英文嗎？講的程度可能對白人而言就有點勉強，所以，同學回答："勉強地"

"hardly"