I hate this pairing. I dislike Riley. I wished Buffy would had beat him into mush and ship him back to Iowa.
I know Joss Whedon was going for an Anti-Angel and give Buffy a chance to have a "normal" relationship, but the fact of the matter is someone like Buffy can't have a normal relationship. She's the Slayer. She's destined to fight vampires, demons, and anything evil. Her relationship with Angel worked. It was sad ending, and I hated to see the couple end, but the relationship worked. Angel meshed in with her world.
Hell, Spike meshed in her world too.
Riley didn't. He was a man of order. He followed his CO's orders, followed the chain of command. In his world, girls were not as strong as men, they allowed men to take care of them, and allow men to save the day. He couldn't even handle that Buffy was stronger than him and better at his job than he was.
He thought the "job" was an adventure, but to Buffy, it was her life. A life that has taken the lives of friends and has controlled her since she was called to be the Slayer.
Riley had no respect for who and what Buffy was from the beginning. Sure, he may have liked it at first, because it's like tasting a new flavor of ice cream and enjoying it at first, then getting sick of it after eating it too much.