Hi! I'm 29 years old. My husband and I got married July 2013. He has an 8-year-old son from a previous relationship. The parenting relationship between he and SS's mother is healthy. We have SS every other week, Monday to Monday. DH and I dated for a year and a half before getting married, so I came into SS's life when he was six and a half years old. Before we married, DH and SS lived with my ILs. From the time SS was 2 until he was about 4, his mom was out of the picture, so he was raised primarily by his dad and grandparents. DH and I are expecting our first LO in about six weeks...a girl.

We're also in the process of buying a house.
So...being a step-parent is probably the hardest thing I've done in my life, up to this point. I was under the impression that DH and I agreed on a lot more things than we actually do. I made my expectations clear, and we discussed parenting philosophies, all before we were married. I never got the impression from him that we would have any major issues.
Now that we're in the midst of the situation, I'm finding that to be painfully untrue. I still think our philosophies are close to the same, but our tactics and management methods are vastly different. He seems to feel some pity for his son, I think..maybe it isn't pity..I'm not exactly sure. But he handles him with kid gloves in situations when the little guy should really probably be in trouble. DH has defended his son to me on several...many...occasions. I've told him that I feel he's always defending SS to me, which makes me feel like they both see me as the 'bad guy,' but he just said they don't see me as the bad guy, and that was about it.
I'm strict, I'll admit. I never fronted though, or insinuated anything other than that I am strict and will continue to be strict. By "strict," I mean that we have rules in my house, and I expect them to be followed. When they aren't, there are consequences. I don't impose any insane rules. Bed time. Restricted time on electronics (that's a pretty new one..it was out of control). Wash your hair and your butt hole. You know. The usual.
Last night, DH told SS to put on a jacket so they could go outside. It was chilly. SS was wearing gym shorts, so I said "Yes, and also put on some pants." DH (in front of SS) said "No, it's not that cold. It'll be fine." Not that big a deal, right? I don't think so, either, it's just all I can take. It was the straw that made the camel feel like giving up. I'm just tired of trying to compromise and work together toward our goals as a family, but being brushed aside or having a child defended to me by the guy who's supposed to have my back. I don't mean "tired" like "pissed and aggravated." I mean "tired," like literally exhausted of it. With all the other things going on right now (great things that I'm happy about, mind you), I just can't handle any more of the opposition.
It probably doesn't help that I'm the most emotional I've been throughout this pregnancy. My husband is a good man. I love him deep and so. He works hard for our family, loves me, even helps with household chores..a lot. But our parenting dynamic is pretty atrocious right now. We've talked about it several times, but he's made it clear he's unwilling to make any changes or compromise on many things, and I don't know what to do with that.
Advice is welcomed. Flaming will probably make me cry. Most things do, recently.

Re: Intro & Vent (I'm a stepmom)
FWIW, my son is 9. We just had an 80-degree day on Monday, followed by a 50 degree day on Tues. On Tuesday he was dressed in light shorts (the meshy-athletic kind) and a similar weight t-shirt. I told him "why don't you go outside and see if what you are wearing is going to be too cold? It got colder last night. He went out and told me it was ok, so I said "well, at least bring a jacket" (because he won't be allowed out at recess if he doesn't have a jacket in cooler weather, otherwise I would just let him deal with being cold). If he didn't want to wear the jacket, that was on him.
Your H stepped up and told SS to wear a jacket - - he was handling it. In a way, you corrected / disagreed with H (implying that he should have noticed the shorts), and now are angry that he disagreed with / corrected you?
You and your H are allowed to be different - with SS and with your LO. If he openly disagrees with you (and I don't consider the jacket / pants issue as "openly disagreeing"), then you need to discuss SS in private.
There is a great book you can get on Half.com - STEP (not about blended families, S.T.E.P means something else). It was actually a course but you can just read the material. It is about natural consequences as a parenting technique. It also deals with if your partner is not on the same page as you. For example, if you have a bedtime of 8 pm, and your H allows his son to pitch a fit and not go to sleep - tell your H "I am going to bed. You can put him to be any time you want - but YOU have to be the one to get him to school in the morning, because I am not going to deal with a cranky sleep-deprived." If your H needs to get to work in the morning and wants you to take over, you need to tell him "If you want me to take care of SS in the morning, you need to put him in bed at the bedtime we agreed upon. *I* am not going to deal with the consequences of YOU allowing him to stay up late. YOU need to handle him in the morning if you allow him to stay up late."
One of the things my counselor had me do was make a list of everything I wanted/needed changed or done a certain way/my way. Then I showed this list to my husband, who scratched out about all of it. I looked at what was left, and decided I could live with that.
In the past year my marriage has gone from on the verge of divorce to wonderfully full of love, plenty of effective communication, and a desire from both parts to work together to support the other.
In short, I thought it was all him, but I realized a lot of his issues were fueled by my problems, and he was much more willing to meet me in the middle and on many things completely come to my side of the field.
If you have already talked to him about how you feel and you're getting no where, ask him about how he feels. Listen. Don't interrupt. Don't try to argue your point or justify something. Just listen and ask him what you can do to make him happier (in regards to whatever the subject is). I bet it will get a much more willing response in more ways than you think, especially once he sees you making effort.
Good luck. And trust me, I am in no way saying anything is your fault or anything. But a lot of people don't respond well to telling them what they're doing wrong.
Edited for typos.
After you are ok with the fact that you feel that way, then you can start to change your inner dialogue way of thinking/feeling about things.
Btw, I think women go through what you're dealing with pretty commonly. Maybe I'm wrong, maybe it's because men don't seen to talk about it as much, but I think women deal with it more than men. But I have absolutely nothing to back this up. Strictly my own opinion. Lol