While it's true that physiologically vaginal intercourse on its own isn't always, for the person who has the vagina, something to write home about, there are plenty of ways to actively make the partnered sexual activity, including slowing things way down satisfying for everyone involved. Your vaginal opening may not look like an open hole like it is in this diagram. How do I keep him from going in the wrong hole? Our bodies are designed to tell us what they need and want by how something feels to us, and what they don't need and want, so you really can trust your gut on this one, and go with what is comfortable, not-painful, pleasurable or all three for you. Your anus the opening where you have bowel movements — poop has a tight band of muscles that need to be relaxed and would make inserting a tampon difficult and probably uncomfortable as well. The first, which is the smallest, is your urethral opening where pee comes out ofwhich is not where the tampon goes or would even fit in the first place. The anal and rectal tissues don't lubricate themselves, as vaginal tissues do, and are even more sensitive to cuts and abrasions, and accompanying infections.
As I said above, the vagina does have an end to it, so you will not be injured by your boyfriend's penis going too far.
How do I keep him from going in the wrong hole?
Your vagina is a flattened muscualar tube that can stretch to open up just like a pocket can open up to fit things inside. We have a great video on our website that gives you step-by-step instructions on how to properly use a tampon. Starting at the front of the body, we first have the urethral opening, where one urinates from. Since your question is specifically about intercourse, I don't have a good sense for how physically or emotionally ready you felt for that intercourse at that particular time, or whether you felt like it was something you needed or wanted to do more for your boyfriend then for you. Slowing things down sexually also has the added advantage of helping you keep things safe and comfortable. The easiest way for you and your boyfriend to make sure you're both engaging in the sexual activity you want, and that you intended to engage in, and that won't hurt either of you, is to talk about it.