As far as I recall PE mostly deals with lesbian experiences, yes. At least as far as love interests go. There's some (forced) hetero stuff, like with your best friend (who can be either guy or gal, but it's only first base with them, so…), some bullies, and a randy coach at school, but no meaningful relationships to build. There may be more content upon becoming
the school slut, but that's end game already and probably not what you're looking for.
Secretary has a few relationships to build and offers both (trans)lesbian as well as hetero content. The story lines are really great, though I can't comment on how far each of the them go. It's been quite large a game already the last time I played – when a plant was just a plant – and has only gotten bigger and most probably also better. I wholeheartedly recommend you pick it up and see for yourself. Alex (be a gent, massage her feet, stay put, and help a lady out…
), Bob, Kurt, and Ms. Antlers are introduced in the first minutes of play, as is your new position as Ms. Antlers secretary. Maybe also play to your first therapy session, after which you should have a firm understanding of what to expect from the game.