Here's my thoughts.
First, you need to seek professional help for your porn addiction. Do NOT go into a marriage without resolving that first. If you really loved her, you would not do that to her.
Second, we become just like our parents. He has a history of sadness, YOU have a history of sadness. So find out what his sadness was all about. Learning about it may help you with yourss.
So you've learned most of your socializing on line, which means you haven't learned the day to day ups and downs, give and take, like most of us. When to apologize, when to kiss up, when to stand up for yourself, when to sacrifice for someone else, stuff like that.
In other words, you haven't lived enough yet. You haven't done the stuff most people do; you were alone in high school, and you lived a frat life in college. You've never learned anything else.
IMO, that is why you feel 'wrong' about the marriage. If you get married now, 5 or 10 years from now you'll be wondering what you missed out on.
I'm not saying not to get married, I just think you would BOTH be better off waiting at least a couple years. Spend some time living on your own and living life - outside of college.
As for your selfishness, I have a great fix for you. You and Beth need to sit down and type in
find a charity to volunteer at
in Google or Yahoo, and choose one near you that you will both enjoy. This will do a lot of things. It will get your gaze off of your own navel so that you learn you can spend time on someone else other than yourself. It will give you and Beth a lot of time together each week (remember, MB wants you to spend 15 hours a week together). It will allow you and Beth to see each other in a good light, which will make her more attractive to you. It will set a lifelong habit of stepping outside your comfort zone and giving back to society. And of course you'll be helping someone in worse shape than you, which will also get your head out of your butt and stop wallowing in self-pity.
Good start for now.
What do you mean you're indifferent?