I agree with LH. Sit down with GF and have a conversation with her.
I would suggest a few things. Ensure son is napping. Sit down with her. Take your phone out and shut it off! In front of her. Then start off with something like: GF, I am sorry you feel unimportant. You are very important to me, and I apologize for not displaying that often enough. You have my complete and undivided attention, and I am willing to listen.
There are many subjects that are likely to be brought up. Be open and listen. Be sincere. Do not focus on fixing the things as much as learning about the things. Let her suggest, and listen to her suggestions for solutions and resolution to the present troubles.
Communication is key to everything. GF is still talking to you. She hopes you’ll understand how she feels. Validate her feelings and gently prompt her to expand upon them. She’s needs to lead that. It’s her feelings after all.
Where this all leads is unknown. Let it be unknown. Act as if. Go forward with a positive attitude and view that you and her can communicate sincerely and openly.
We often make our fate through the smallest of intent. If you go at this believing it is going to fail, it likely will. Small subconscious mannerisms will influence in that direction. And likewise, positive usually begets positive. And positive is a much better mindset for interactions.
D
Feelings are fleeting. Be better, not bitter. Love the person, forgive the sin.
