Five years is a long time to date someone. You got married knowing that the kids would be there and of course you are going to argue about them. It's not easy to adjust when you have kids involved but the most important thing is that you love each other and that means that you should be able to communicate your thoughts and feelings. If her son is lazy then perhaps you need to talk to your partner about it and come up with something for him to do. Maybe he is lost and needs some guidance. If not then talk to your partner in a friendly manner to see what you can both come up with. Life is going to be difficult to adjust to with kids that have lost a parent and have a new male presence and separating is not the answer if you love her. Talk calmly and find solutions before you argue.