Well I read through what you have so far and I've some feedback for you as per your request.
Art: I think the art is great, you've got a very smooth style and a texture that feels very much like it belongs in an animated film. You keep your character on model and your lines are very smooth, so it all comes across as a strong work in the art department. I enjoy the use of shapes in the back ground characters that contrast them with Dee and River. I also appreciate that your comic isn't just a sequence of shot, reverse-shot. You have movement either by having a character grab their head, make a half twist or swing their legs of a bench. There's always some kind of movement that keeps the art feel alive so, kudos that's really awesome.
Pacing: First I'll say this, I'm glad you started in the action. You have a brief scene between River and Dee and bam, right into a fight. It was a good way to start and set the tone and the energy for the rest of what you have up so far. Now overall you've got a snappy pace to your story and this is good. It'll save you from dragging through scenes and keep your audience on their toes. Some parts of the pacing sometimes feel upended, however because a scene has to stop for River to make a comment. In the very first fight scene, five of the panels/shots were dedicated to a gag about River fearing she might be pregnant, when Dee is expecting her to throw the gun back to him. I actually thought this was funny but, the scene having to stop so she could make the joke and it felt like Dee would've already been punched in the face at that point.
You're actually great with visual gags, so my only recommendation in this scenario would be to up the ante with the fight. For instance if Dee had been throttled and really needed her help while she was complaining, all the while his situation grows worse, it would've kept the scene feeling like it was in motion (and still went along with the humor you invoked). You're great at keeping things in motion, so this is just a small suggestion of how you can keep that momentum and make your joke, without stalling the momentum for the joke. It would also make Dee's punchline at the end of that scene that much more of a burn, because his peril had increased.
My advice is to think about the number of panels you're going to use to tell a joke and see if you can utilize the scene/background/environment etc. for the jokes best benefit. The best part about visual mediums is sharing visual humor and you're already pretty good at it so, that'd be my recommendation there.
Humor: I find the humor pretty genuine. Your main characters have a good type of snarky chemistry between them that works. One of the caveats I have in regards to the humor is this: make sure that your sexual humor isn't mostly concentrated on River. Now yeah, there were a few jokes about Dee that were sexual and they were funny, and many of the jokes around River are funny, however, innuendos always concentrated around a single character tend to wear over time. Think of all the stereotypical guys in horror movies who are only in it for the prospect of sex. We all groan and roll our eyes when that archetype comes on screen because all the jokes are done to death and nothing new can come from it, so it becomes lazy writing.
I don't think you're anywhere near that level but, it's something to bear in mind. If all the jokes around River are more concentrated on sex most of the time, they'll lose their punch and become expected after a point. One of the things your comic has going for it is that it feels more unexpected and even if you're using jokes that have been done, you've made them happen in such a way that they're still fresh and a good laugh. I also didn't anticipate the gags so they were a nice surprise. (That bit with Dee trying to ditch cops by busting down a wall to find a room full of them, made me laugh. I loved it. No matter how much he's razzed River, he's muddled things up just as much and that dig at his expense really worked.) I'd just look out for the overuse of jokes so they don't go stale, and then invoking referential humor sparingly (which, I don't think you'll have a problem there, you have strong writing chops).
Dialogue: It flows well and it doesn't slow down the stories pace, you don't have a bunch of word bubbles with walls of text in them so you're doing fine there. I did notice this bit here that I think you might need to reword because I had to read it a couple of times. In #5 Dee says this: "I wasn't the one sprinting off the bar with that being." I wasn't sure if this was due to Dee himself, as previously he didn't seem to muddle his words. My first thought was that it would be "I wasn't the one sprinting out of the bar with that being." So, it might be something you'd want to reword unless it's a quirk of Dee's.
All in all, I think your comic is a lot of fun. It's charming, your main characters have charisma and I'm interested to see where it goes next. I hope that the feedback I have for you is useful and I wish you luck with your work.
If you have enough slots and if you have time, I'd like to see a bust drawn of this character if possible and I thank you in advance regardless. It's a lot of work to make OC pictures in exchange for feedback, so I appreciate your effort.