It's basically solo ending, although there is a weak poly ending that you can get as well (as in, you don't actually get the girls together, unless that happens in the upcoming epilogue). I think there's exactly one threesome in the whole game.
The MC is not really any of those words you listed, IMO, although he does have some badass moments. I'm not really sure how I'd describe him, but in the words of one of the side girls at the end of the game, he's "normal", which I think is refreshing. He basically has special forces training, but he isn't a bully and rarely gets into a situation where he needs to rely on those skills. He's a bit of a softy, but will defend friends and family to the hilt, with fists if need be. He's smart and caring, but I don't think you could ever call him wimpy. Despite some emotional/relationship issues (which serve as the catalyst for most of the story) he's probably one of my favourite MCs, certainly one of the most likeable.