The non-standard spelling < loveable >
Given the fact that suffixes with an initial vowel letter replace an immediately previous single final non-syllabic < e >, here is the expected result of the construction < love + able >.
lov + able ➜ lovable
The editing houses, however, are not unanimous; many stipulate the spelling < loveable > in their publications. This might be regarded as non-standard.
What is ‘standard’ conforms to the structures, patterns and conventions that apply to the overwhelming majority of spellings of English words (but not necessarily loan words, proper nouns, exclamations or slang).
You could organize a debate among students on the subject of the relative merits and demerits of the spellings < lovable > and < loveable >.