Everyone feels sorry for Desmond, but why?
Everything that's happened to him he brought down on himself. If what we see in Flashes Before Your Eyes is an accurate representation of what happened (minus the intervention of that white haired lady in the jewelers) then the main reason he split with Penny and entered the boat race was because her father didn't like him...
Big deal! Not everyone gets on with their in-laws.
If he really loved her, he would have made a stand with her but no, not our Dessy. No, he goes running off to prove to her father that he is a great man, shattering Pennys heart in the process (Yeah, that's really the mark of a "great man", hurting the one you say you love). Penny had made it clear that she had made her choice, she loved Desmond, she wanted to spend the rest of her life with him and didn't care what her father would say.
He even got a second chance at the stadium at the end of season 2. When she asked why he didn't write to her while he was in jail he could have told her the truth but no. She came there to find him, to tell him that she still loved him and still wanted to be with him, but he brushed her off, and again he gave the excuse that he had to prove something to her father. For Christ sake man, if you want to show that you're a great man do want any real man would do, stand up to him. You tell him that you love his daughter, she loves you and there's not a damn thing he can do to keep you apart.
Now he's sitting on the beach, crying, "Oh Penny I love you. I love you. Gimme another chance! Let me go back again!".
To be honest, he doesn't deserve another chance.
Apart from that he's a rather nice guy, heh.
I know it's not in the nature of this particular board but if you have a different view on Desmond's actions then please say so. I'd like to understand why everyone feels sorry for him.