What are some ways to prove you love your girlfriend more, without actually touching her?

Spend time with her. Limit the amount of time you spend with other girls, it really would hurt her. If she seems isolated or upset then talk to her about it, only leave her alone if you are *really* honestly making it worse, which is hard to do. Text her so she knows you are thinking about her. Invite her to do things that you both enjoy, like the movies or something. Maybe have her go to your house or vise versa and watch a movie there if either of you don't like the theaters. If she grabs her wrist with her other hand that means she's insecure. Don't over-compliment her if she feels awkward about it, but occasional complimenting does great. I know you said without touching her, but putting her arms around her at the movies or something, even if it's just on the chair (but still about her) does great. Or touch her hands. Just be there for her no matter what.

I hope I helped at all or that you get a better response from someone else

-hang out with her rather than going out with the guys for a night
-write a hand written letter, describing all the things you love about her
-look her in the eyes while she's talking, actually listen to her
-tell her face to face how much she means to you and how much you love her
-send her Goodmorning and goodnight texts or if you really miss her, call her
-in any social media bios, include her name with any cute loving emojis
-call her cute nicknames
-ask her if she's okay if you think something is wrong
-(I agree with the other person)don't hang around too many girls, make her your actual one and only. Also, don't talk about exes unless she brings it up
-on any holidays, birthdays, or if she's just on her period or sick make sure to make time for her; buy chocolates, ask if she needs anything, treat her extra sweetly, be there for her, don't forget dates, etc.
-take her out on dates
-tell her some secrets
-learn more about her, ask about her favorites, dislikes, find common interest
-show off any talents like: singing for her, cooking for her, dancing with her, etc.
-always apologize, even if you know you're right
-open doors for her, help her into the car, offer your jacket or anything when she's cold
be the true gentleman that you've heard about that'll make her head over heels
Hope this helped, good luck (: