In his two dialogues that deal directly with love, he excludes sexual relations either implicitly or explicitly. In “Sympsium” love (eros) allows you to reach an understanding of the form of the ‘Beautiful’, and love creates goodness, and people can only ‘give birth’ (besides physically, also mentally by creating things) in goodness, so that’s why they seek it, to create and achieve some immortality through their creations.

In “Phaedrus” he explicitly tells how one of the three parts of the soul (mind) is a wild horse that pulls the soul in lust, and reason (the charioteer) then proceeds to pull back with all its might as the emotional part of the soul goes towards sex, as love is there to remind the soul of beauty, which is the souls nourishment, not to “mount [others] like an animal”. That’s basically the tl;dr of his writings on love in those two dialogoues.

Platonic solids are solids Plato mentioned in “Timaeus”.