I think it actually helps to look at the entire Riker arc (Unintentional though it may be) I use to think they way you do, but now I look at how they rounded out the character (& yes, I'm even including TaTV) It's clear that his experience on the Pegasus was a skeleton in his closet for him. It haunted him. That he was a go-getter as a young man, who may have built his fast & impressive early career trajectory on the recommendations of a corrupt captain who covered up their blame, & drove himself to stand out heroically, because of the guilt of having played a role in the deaths of so many on that ship, could be the very reason why once he was in position to actually claim that prize of being a Starfleet superstar young captain, he subconsciously shunned it out of a feeling that he didn't deserve itI agree. For a guy who gave up so much in personal life costs in order to achieve his ultimate goal of becoming a captain, and then for him to turn down so many opportunities is just silly and completely suspends belief.
You can even retcon him getting back together with Troi into that, being that she was the one who helped him deal with his guilt over the Pegasus, which shortly thereafter led to him finally taking command of the Titan