Hi ... and welcome to the Forum
It sounds as though it could be a dead cell in the battery, you would need to carry out a heavy duty discharge test on the battery to determine this.
There are many other possibilities such as an interior light on, short circuit in the wiring, etc.
Would advise getting it checked by an auto electrician as it will soon irritate the hell out of you every morning to have to jump start it.
Let us know how you get on with it.
Cheers Trevor