I think a lot of you have really good points here, especially @AnnaLandin, @scythe, @ratique and @starlightcityentert.
Frankly, @jackieuy127 part of the reason you find that 'hanging out and slapping the other's shoulder" not working is because it's an incredibly tired trope. It's not new. It's not different. It feels the same, because there's thousands of other scenes across thousands of other comics that do the exact same thing. This is why knowing your romantic tropes is so important. When you know those tropes, and just how pervasive they are you can either find a way around them or break them entirely.
As for what makes a romance good? One of the best things I've learned about writing Romance in my travels has been this: Your characters need an Ocean.
You know that old song "Somewhere Beyond the Sea"?
Somewhere beyond the sea. Somewhere, waitin' for me! My lover stands on golden sands, and watches the ships that go sailing!
Any good romance needs something separating them, and that doesn't always mean something literally. It could be a literal ocean, but it could also be class, family or their own values. As your characters begin traveling across their metaphorical ocean, they'll run into sea-monsters, and friendly dolphins. They'll be captured by pirates, they'll get lost, see beautiful sunsets and hear a mermaids song. All of these encounters will either push your characters closer together or drift them farther apart. One character might lose hope and return to their original shore for a while, only to strike out again when they can't stand it any longer.
Diving into this idea further let's break the metaphor down a bit:
Romeo and Juliet. Their ocean is their families and the feud that plagues both houses. Their story is romantic because they're literally not supposed to be together at all - it's the individual couple who wants to be together vs a society that doesn't. Their friendly dolphins are the friar who marries them, and Angelica, Juliet's Nurse and surrogate mother figure. Their seamonsters are Tybalt and Count Paris. It's a simple story, and what makes it so romantic and tragic is that the only way they can be together is in death.
Your job as the writer is to do the same thing as a professional in the art of seduction. You must tease, flirt, and entice your characters into wanting more of each other, but not letting them have it. Not until the tension and desire is so high, nothing else can happen but for them to fall into each others arms - and WHEN that happens? Immediately finding a new ocean they have to cross. This doesn't mean your characters can never be happy together, of course they can, but after the point they're together love is only interesting when it's tested. When they have to stand together or die apart, otherwise you're left with goo-goo eyes and mindless sex (which can be nice, but after a while it just gets old).
Chemistry is important. Characters being well developed is incredibly important. Understanding that love comes in many forms is important. But story? Story trumps all of it. You cannot have a love story without...well...story!
-C