The whole point of talking about important issues with your partner is to reach an agreement. So both of you need to be willing and ready for a little give and take.
You should never 'give in' on things that are really important to you and compromise should never be about one person getting everything they want. Just be prepared, compromises can't always be reached, and you need to be ready for that too.
Try explaining to them that you'll feel much more comfortable, if you can talk things through.
Good relationships rely on good communication. When communication breaks down, little problems can quickly become overwhelming. Sometimes you can get into a rut of not really listening to each other and arguing lots. If this happens, it might be worth finding a bit of outside help. You might be able to get things back on track through relationship counselling or read our advice on rocky patches and splitting up.
It's not possible to talk about every single thing that might happen during sex, so don't be afraid to speak up at any point, if something is going on you're not happy about. It's perfectly OK to have boundaries.