Well I left my village without going on pause! I went away for a day or two, I found my only two female villagers were weakened, and they don't seem to be regaining health. one of their health bars is empty. Are they just going to die? I am really worried.. I'm the furthest I've ever been.. and now they have no females to reproduce if these villagers die!

The only thing to do is to make them eating again and again!
And also, give them the less tired task as farming, even as healing. Don't put them at the research table.

OK thankyou. so will their health bar go back to normal if they don't work too hard?

It will be long but yes! The best is to make them eating!

And, when you quit your game, don't forget to select 1 (or best: 2) villagers as healers. If they are not selected as it, they'll not heal a sick villager by their own, even if they have some healing skill! Don't let your vilagers alone without doctors!
And also, select 1 farmer to be sure he'll harvest or forage when you are not here!

Oh Thankyou so much! there is hope!

You're welcome! Good luck!

Best of luck to you. Normally, I have a rule: No lagoon, but in this case, use the lagoon.