Love 1971 is based on Super DC Giant #S-21:
Love 1971 reprints the cover and main contents of Super DC Giant #S-21.
It does not include the Love, Tina letters page. However it does include three one-page instalments of the Mad Mad Modes for Moderns feature. This is a feature which appeared in a number of DC romance comics between 1967 and 1970, and was used as filler in various other K.G. Murray issues. Here's a sample Batman-inspired sample as printed in Love 1971:
The Beauty Bar is another one-page feature, in this instance titled Do's About Hairdo's..., which hails from Girl's Romances #153.
Other instalments in this series have been referenced in passing previously on the blog here and here. There are possibly more issues in this annual series, maybe appearing as Planet Series issues.