After a few less-then memorable dates ...
After a few less-than-memorable dates
Whenever I see a "then" in place of "than," I like to give the writer the benefit of the doubt. If that makes me a chump, so be it.
The hyphenation is even more interesting: Writer made a compound to modify a modifier (memorable) instead of uniting them to modify the noun. Interesting choice, but, as everyone knows we copy editors are drunk with our own power, I changed it.