I could sit here and write out links for all sorts of things to do in Estes Park for romantic couples. Instead, I'm going to plan two or three days for you and leave it at that. Basically, I'll plan what I know my wife would like:
Stay at a romantic hotel or cabin. The Della Terra in Estes. It's expensive but very romantic and classy. I'd search for a cabin rental with a private hot tub on the river as well. Get in early though. The really nice places book up fast.
Go shopping downtown. Guys may not dig it all that much, I know I don't. But she will. It's important to do things that interest both of you, but not do it to the extremes. Stop in at Elkins and sip a little bourbon and hit Snowy Peaks Winery while you're downtown. Get a little loose and have fun with it.
Go on a short easy hike with fewer people (Lumpy Ridge) and/or rent ebikes and ride around beautiful Lake Estes.
Rent a Jeep and hit an easy trail with a beautiful view. Guys, don't get all stupid here. Some girls don't want to be jarred around all day. Hit an easy trail or just explore around the backwoods. We can suggest some great views and remote locations. Better yet, rent for your entire stay and catch some secluded and very romantic sunsets. Who knows what else might go down? Could be an amazing opportunity to pop the question.
For breakfast, I like the Big Horn. It's a favorite local joint.
Leave a little time to make yourself available for other things / activities that might pop up. In other words, don't plan every second of the day. Take it easy and explore with each other. For that matter, consider never getting out of bed.
I've been with my wife for over 30 years. We are still romantic and very much in love. Personally, we've never had much luck doing romantic getaways in the big city. We do try at least twice a year. It just never ends up being as good as a small mountain or beach town. So far, our favorite places are Costa Rica, the Bahamas, and Estes Park. We are interested in the Smokey's. It's one of the areas we haven't tried yet. If you have suggestions for me (anywhere), hit me up at goodtaters@gmail.com
Andy Hitch