Is it normal to not feel so in love with your partner from time to time? ?

In relationships, we sometimes have other things on our minds besides sex and cuddling, as you know.  Your gf sounds childish

Sounds normal to me. She sounds a little clingy. A relationship where you aren’t willing to miss each other a little bit, you won’t last. When you are out and about do you see couples always on each other? We tend to cringe at those few couples, but most couples can go without PDA and just act like normal people. Tell your girlfriend she needs to find something else to do rather than wait for your love every single day :). If she had legit activities to do, she wouldn’t be so concerned on why you haven’t texted in a few hours 

The idea that being boyfriend-girlfriend means being on a date 24/7 is an idea that doesn't work. If she wants all together time to be like a date, then best not to be together when you'd rather not behave as if you're on a date. If you two are sharing a home, then there has to be recognition that there is such a thing as too much togetherness, that one needs private time for oneself even if that has to happen in the shared living room. 

"I'm not feeling sociable tonight; I'm feeling solitary and want to be left alone." That's a request that should be honored. But that mean it's OK to be a butt head about it. You can't use "I'm feeling solitary" to avoid some conversation your partner wants to have and you don't. If you're not up to that conversation tonight then you'd best be up to it tomorrow. 

And along with there being too much togetherness, there is such a thing as not enough togetherness. How much togetherness is right is different for every couple.

Sometimes young people don't understand that life is generally kind of dull. You get up, go to work, come home, do some tasks around the house, eat, and hang around being tired and dull until bedtime. And then you do it again, day after day. 

That you're sharing your home with someone doesn't change this. Life continues to be sleep work eat sleep. The idea that your life would be more exciting if only your partner wasn't holding you back, if only your partner wasn't around -- that's nonsense. Your life would still be sleep work eat sleep except there wouldn't be anyone to say "Hi honey, I'm home" to. 

That sounds perfectly normal.  

I'm in love 24/7 it never stops