Was it? I honestly don't remember. If so, my apologies for a stupid question.
Is there a reason the Welsh for deer is absurdly similar to the Welsh for love?
No, just a coincidence.
caru is related to câr which is from Celtic karants while carw is from karŭos (which is related to Latin cervus).
A bit like how it's a coincidence that friend and fiend in English are absurdly similar despite meaning more or less the opposite. Or, for that matter, that cleave (= split) and cleave (stick to or adhere to, as in "and shall cleave unto his wife") are so absurdly similar as to be completely identical today despite meaning more or less the opposite -- they come from completely different roots.