Usually various grammatical clitics (e.g. verb's person) join the main word through concatenation in spelling, but by Nûrlâm convention they are written separately as stand-alone words when phonemes/words boundaries otherwise may produce:

• two consecutive vowels;
• long, hard to pronounce consonant clusters;
• digraphs.

However, when written in Tengwar, all words will be written without spaces anyway. But Latin separate spelling will ensure that no sound combination into a different character will occur in Tengwar transcribers.