You have a leak. You need to take it to a shop where they can put dye in the system. Then they can use a black light and find the leak where the dye came out.
When the engine is running and if the check engine light is on it has nothing to do with the battery or alternator. The bat light may come on when the key is in the run position but the engine is not running, that is normal. You need to get the codes read from a dealer or auto zone will do it...
As long as you brought her half finished drink out to the car for her to finish, then she should be grateful that you care so much about her happiness. lol.