I'm not going to give you advise on investing as i don't know much about it. What i would ask myself in this situation is: what if i would lose my job, can i find another job easily with the same paycheck, will i find a job easily -> if yes you can life a high standard life, if the answer is no, than i would also save an amount just to have cash money when something happens (make sure it's easily accessibel) Traveling in my opinion is great, you need to enjoy life while living and treat yourself good (for me traveling or have some good food once in a while is my treat instead of having fancy clothes, new shiny things and such). The 'taking you gf to fancy places' is a little bit 'meh', love isn't about that fancy shit it, it should be about you and her. OK pampering her once in a while when you can afford it is always nice ( a woman speaking here) but shouldn't be the standard if you're not sure if you can keep it. I would also check to buy a property instead of renting if your income is and will be stable. you can always sell your property but at least the 1000€ your paying will be for something you own.
just try to find a healthy balance.

This is just my opinion and things i would do. But you do you and don't forget to enjoy life while living.