Where I come from, we have an ironic saying about love, it could be translated into English as:
Love is warming, but coal is coal
(Or perhaps less literally as "Love is heartwarming, but coal will always be coal.")
I'm trying to translate that into Latin. So far I've come up with:
Amor calefacit, sed carbo est carbo
Amor calefaciēbat, sed carbo erat carbo
I'm really uncertain whether the present or imperfect is appropriate. Would someone be so kind as to improve on my attempt? I'd probably prefer a plain and simple translation over eloquent / poetic ones.