What does 惟覺 mean here?
I think  無情 is not "unconcerned", especially with the 總 there; more like "as if there had never been anything between us" (好像我們彼此從來沒有過半分戀情)

惟覺 = 只覺，但覺 etc.

It's a little bit like German doch, indicates an attitude, very hard to express in English. a little bit 無奈, perhaps? resigned sorrow; but put that in a translation and its spoiled.

"Now that we're sitting with wine glasses in front of us, I find that I can't even manage a smile."  Just a sentence, not poetry.

I agree that 心/芯 is the pun intended.  But since wick and heart are not homonyms in English, I'm stuck.  A truly tough poem to translate.