Hi and welcome to the forum
The gourami in the picture looks like a female dwarf gourami. She does not look very well and is skinny, has sunken eyes and tattered fins. This could be from old age or stress or disease (virus). I am going with stress and old age.
How often do you feed the fish?
What do you feed the fish?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
Can you post a picture of the other gourami?
--------------------------
Try feeding the fish more often (3-5 times per day). Feed them a variety of dry, frozen (but defrosted) and live food. Raw/ cooked prawn/ shrimp is a good food to condition fish. You can buy it frozen form a fishing store (in the bait section) or from supermarkets. Keep them frozen. When you feed the fish, take one prawn and defrost it, remove the head shell and gut (thin black tube in body) and through these bits away. Use a pr of scissors to cut the remaining prawn tail into small pieces and offer 1 or 2 bits at a time. Let the fish eat until full then stop feeding and remove uneaten food. Put the remaining prawn tail in the fridge and use later that day. Use a new prawn each day so they are fresh.
You can also get marine mix from pet shops. It is prawn, fish and squid that has been blended up and frozen into little blocks. You keep them in the freezer and take one out and feed it the same way as you use prawn.
Do a 75% water change and gravel clean the substrate each day for a couple of weeks.
Clean the filter if it hasn't been done in the last 2 weeks. Wash filter media in a bucket of tank water.
--------------------------
You need a picture on the back of the tank to make the fish feel more secure. And some floating plants like Water Sprite (Ceratopteris thalictroides/ cornuta) would help the gouramis and tetras feel safer. Water Sprite grows on the surface but can also be planted in the substrate if you get too much.