The Mummy on TV last night and was reminded again how much I love that movie. I never actually saw it in the theater mostly because I thought it was going to be just another action adventure with the forced romance and funny sidekick. Yes, it has romance and yes there are several characters that could be considered sidekicks, but there's nothing forced about the romance or the humor in the movie.
What I find interesting is if you read the script (I'm not sure what version it is, but it isn't the shooting script) the romance between Rick and Evy is much more of your traditional action-adventure forced relationship. It doesn't have any sparkle to it. They antagonize each other yet seem to kinda like each other. The movie gets it right. Whether these changes were made in subsequent drafts or after Brendan Fraser and Rachel Weisz were cast I have no idea.
For those interested in writing an action-adventure with a touch of romance I highly recommend that you study The Mummy as an example of how to get it right. It isn't an instant romance, but one that builds between the two of them as they get to know each other. They fight, they banter, they flirt, they have sweet moments and hot moments, but the point is the romance flows. A lot of that flow can be credited to the chemistry between Brendan and Rachel, and like most of my analyzing I would love to know how much was written in with them in mind, improvisation, etc. It's the beat of the romance that builds throughout the entire movie that make it work. If you wish to include a romance in your action-adventure don't forget that the beats of the romance are just as important as the beats to your adventure. If you're really good those beats are often combined and mingled together allowing you to build the story and romance as one.