The wonder women are to be prepared for an extreme reaction, from rage to silence. One giant supposition I have made in the scenario at hand is that the ex has an interest in you. So now we can assume that your best friend is cool and you have made a move. You start to date and an exclusive relationship is around the corner. Out of respect to your best friend, there are a few steps you should take, Limit his exposure to you as a couple, Make a concerted effort the first month or two, to ease him into the new reality. Limit your public displays of affection, Once you start to socialize as a couple, you may not want to make out in front of him or tap that behind. Display your affection with class and not in a gratuitous manner. Do not complain or seek his advice, It could depend on what type of person he is but as a general rule, I would not advise you to go into detail about the relationship wonder women. If you have a problem with her behavior for a particular reason, deal with it on your own. He had to and so should you. A discussion about her could be painful. No sex talk, Unless your best friend should fall under the depraved category, refrain from pillow talk. Gossip with another friend who has no association with him, if you must. An obstacle or two is inevitable. His ex and your new woman may need reassurance now and then that the woman has not come between the two of you. Both you and your best friend must make an effort to let her know that the opposite is the case. On the other hand, the woman may need a lesson in class in order not to flaunt the relationship in his face. You need to take a stand from the outset to ensure that everyone is on the same page. A hidden agenda or unspoken opinion could destroy more than one relationship. Jealousy can make women crazy and it can lead otherwise normal women to do all kinds of insane wonder women.