If you are not yet married or on track to be married to your boyfriend, your contact with the other parent will probably be minimal. If, however, you are in a long-term relationship and the children are under eighteen, it is likely that you will encounter the other biological parent. It is important for your boyfriend to take the lead in introducing you. He will know when he is ready for you to meet his ex, and you should let him know when you are ready. He should also check in with his ex, and be respectful of her feelings about when it is appropriate to meet you. It doesn't need to be a huge production, and is certainly on a different level than meeting the children. It is possible she will just want to say hi when you pick up her son if she is used to the idea of her ex having a significant other. If, however, she has a small child and is nervous about the child staying with you, she may want to have a more formal meeting. If there are hard feelings around the whole breakup, she may not want to meet you at all right now, and that is something you will need to respect.

Your boyfriend should inform you whether his ex is very angry about the situation or is fine with it. This can determine where you meet her for the first time. When the situation is still strained, meeting her in a neutral territory such as a park or playground can be more comfortable for both parties. Hopefully, the situation is amicable and you will be able to meet her at her house or at your boyfriend's house at a time that is convenient for everyone.