I'm using this Curry paste but my girlfriend doest like too spicy, therefore the flavor is really bland.. how can increase the flavor without make it too spicy?

I'm using this Curry paste but my girlfriend doest like too spicy, therefore the flavor is really bland.. how can increase the flavor without make it too spicy?

I did a search for Gelbe Curry Paste and found the product in your pic in a result from Amazon.
Based on what I read in a review, you add coconut milk to this curry paste. Therefore I'm hopefully correct that you are toning down the heat and flavors by adding more coconut milk or other milk. So after you tone it down, you want to add flavor back but not add more heat.
The product description lists the ingredients as:
Product of Thailand Dried Red Chili, Shallot, Garlic, Lemongrass, Salt, Galangal, Tumeric, Cumin, Coriander Seeds, Spices
You can add flavor back by adding some of the listed ingredients (to your liking), but not adding more chili. In the US ingredients are listed in order of amount, highest to lowest. While this may or may not be the case here, it may help with deciding which to add more of.
You'll likely have to play around a bit, but hopefully you can get that flavor back.
why not try making your own curry paste? I usually use curry paste from cans but once i tried few recipes, I never looked back. I like this one particularly
Also you can just add crushed ginger garlic while adding the sote ought curry paste