It sounds as though you, your son, and his father have an open and healthy relationship. This is terrific because your support and understanding will help your son make the best decisions that he can for himself. "Being there" for him now — as you are — will likely create a foundation from which he can feel comfortable to come to you with his concerns and problems in the future.

Nevertheless, you are right — it's tough to be a supportive parent on the one hand, while you disagree with your child's choices on the other. This is, however, a typical challenge we face as parents: when our children become young adults and begin to develop their own values and assert their opinions and desires, which may be different from our own. Many families — maybe even most families — face some difficulties during this transition as our children become adults.

The teenage years are an important, formative time as young people change and learn about themselves and the world around them. And exploration is a part of trying to figure out their place in the world, which includes sexual exploration. It's very normal, but it can be difficult for some parents to face the reality that their children are sexual beings who are growing up, especially when they become sexually active. But it seems as though you are very aware of this and have reckoned with the fact that your son has become sexually active. So then the next step is to reinforce your difference of opinion while maintaining an open and supportive family environment.

The most effective way to do this is to have an explicit conversation with your son about your thoughts and feelings. Set up a dedicated "meeting" time to sit down with him and have a talk about your concerns. But before you do, take some time to think about why you feel the way you do. Are you worried that he will lose focus on his schoolwork or his future plans? Or are you afraid that his girlfriend may become pregnant? Is it a concern about sexually transmitted infections? Be prepared to tell him your answers to these and other questions. Simply disagreeing with your son's decision without a reason or explanation isn't the best way to keep the "lines of communication" open. The same is true for whether you will allow your son and his girlfriend to be alone in your house or his bedroom — think about the reasons why you would allow it and weigh that against the reasons you wouldn't. Is there some compromise you can make? What choices will they be left with? Will they be safe? Remember, as the parent you certainly have the right to set up limitations for your home, but be clear with your son about the reasons why you have decided to create those rules. You have already done a great job ensuring that your son and his girlfriend know how to protect themselves from the physical risks associated with sexual activity, including pregnancy and infection. So when you are ready for this next conversation, consider discussing the non-physical aspects of being sexually active. Perhaps you can talk with your son about the emotions that many people experience when they have sex with a partner, such as feelings of deep caring, love, and vulnerability. Use this opportunity to talk with him about his emotional well-being — check in about how he has been feeling since he began having sex with his girlfriend. He may or may not want to discuss this with you, but giving him the chance to talk about his feelings is a great way to show your support.

It appears that you and your son's father have been very straightforward about your feelings and opinions — continue to be that frank with your son, so that he understands your point of view as you continue to be as supportive as you can be. But it is your home, and the decision about what you can live with is yours. The trick is to come to a place that can benefit everyone. That may take a lot of conversation and negotiation.

In order to keep the lines of communication open, you must appear calm and comfortable with your child because if you show strong signs of disapproval, communication will shut down. As much as you may disagree with your son's activities, in reality, if he wants to be sexually active with his girlfriend, he will find a way to do so, with or without your approval and with or without your knowledge. The most important thing that you can do at this point is keep your son safe and protected by giving him all the information about birth control and sexually transmitted infection. If you feel that your son and his girlfriend shouldn't be sexually active, and you don't want them to be sexually active in your home, you may still be able to acknowledge your son's right to privacy. Perhaps allowing his girlfriend to visit his room with the door open is a good compromise. If you disagree with what they are doing, you can continue to let him know in a considerate way. And you can keep providing information — and condoms... This is all a part of growing up — for all of you. Good luck!