I think it'd take a lot more than a woman to make Dean grow up- and if a woman could make him change, she'd have to be a very special woman.

In my opinion that changed him a lot -watching all those people he considered close to him or even family through the years die, I think changed him -along with the whole Sam responsibility thing too!!
Dean has grown up.. Not the same guy he was..even with women. He appears more caring..

The reason he was unfaithful to girls in high school is because he's afraid of any commitment outside of family. He knows that he can't afford them. When they start asking for stuff he knows he can't provide[any kind of normal relationship], he starts getting ansy and seeks escape by making it all one-dimensional...all about sex. Because that makes it simple and easier for him to handle. If it's just about sex than he doesn't have to be honest about how he really feels, he doesn't have to think about what he's missing out on [real love, meeting the parents, getting married, starting a family of his own- normal life].

The only reason he appeared more faithful in later years is because he was so rarely in a situation where he was regularly exposed to one woman and was able to form any kind of relationship with her. Cassie obviously being the exception. He's perfectly capable of being faithful...as long as he doesn't have any other demands [family/hunting] that would draw him away, make him think that he can't afford to be in a relationship and therefore try to sabotage it. I think when he was with Cassie was when Sam was at Stanford. He was probably trying to form something more, thinking he had a little leeway on the family front. Not having to look after Sam. But he was unable to let go of hunting and his father and when he was honest with Cassie about that, she shut him out. Which made him determined to never get that close to another woman again. And his life is a long string of one night stands. Simple, no demands and no threat to his hunting lifestyle...or his heart.

I think he likes Lisa and is capable of being faithful to her... he has no reason to sabotage it any longer. He no longer has to look after his family, he's promised Sam to stop hunting...he can afford to be in a relationship now.

I can't talk about the Lisa thing because i'll just get super mad and go into super bitch rant mode. :P I am so damn passionate about this show ! it's kind of crazy. LOL

but I agree with fanfly.

I believe he has changed.He might still not find it easy to commit but the way he treats women has changed..
I totally agree with shomill she needs someone special and with tazoulini that he has became more caring and has grown up.

Its the hunting that kept hiim from settling down, now that he no longer does that he can be a one woman man. Before it was job-to-job town-to-town so all he was really looking for was a quick hook up. He wanted to be with Cassie but she shut him out.

100% Agree with fanfly..

I feel that after losing so many ppl who were close to him he now realizes how important love is. Rather it's family, friends, or even Lisa and Ben :).

if i losted all the ppl i loved i would change too

Then again ... when he becomes a father.

I think he just grew up a little, realised that his cheating was hurting those girls and that hooking up with women in bars was a better option.