Except the whole Rogue & Gambit mini-series was about them confronting their past and their entire relationship with each other, and realizing that they did in fact love each other. (Well, more Rogue. Gambit always knew.) They may not have done much soul-searching before the wedding, but there was an entire mini-series devoted to that process.
I would like to see more sweet, romantic moments too. Ultimately, though, I've come to terms that a Rogue & Gambit comic cannot be written like Rogue & Gambit fanfiction (i.e. all emotions and sex), and be a success in the mass market. It has to focus more on telling a story that makes sense for a mainstream superhero comic, rather than lingering on the moments between that story. Now, I'd love an issue that was full on fanfiction tropiness, but I doubt sales would agree with me.
In that kind of story, Rogue & Gambit can't say "I love you" as many time as my husband and I say I love you. Which is multiple times a day, usually for no real reason. They also don't talk about mortgages or what to have for dinner or what they're going to do this weekend or 90% of boring married person dialog.
Also, when characters say "I love you" in a superhero book, it tends to mark a deeply significant moment. You notice the only time Gambit says it in MMX is when he's doing that possible suicide run through Deathbird's ship. It's punctuation for meaningful moments.