Choose the right partner, because friends with benefits doesn't mean this one has to be your friend. "Friend" may be a fairly broad word, but in general, a friends with benefits relationship should be an acquaintance. They shouldn't be the first people you call in an emergency, nor should they be the ones you can talk to most anxious all night. They should be someone you like physically, treat you well and make you feel like you are in a safe space, but, for one reason or another, they are not the one you can see yourself in as monogamous people. If they are someone you think can be a friend, you have to realize that this can be a bit difficult to manage.
Make sure that both of you look for the same desire of this mature hookup. Obviously, casual hookup is all about communication. Make sure you all understand that this is just a physical, casual way to avoid hurting your feelings later. You don't have to face each other with the mentality that we are good friends, but you need to be open-minded and frank, not to pursue more things, not to exclude others, and there is no harm. If two people don't feel hidden, this level of openness of adult affair dating shouldn't be that difficult.
When it comes to good friends with benefits, you need to be transparent. If you say you want a casual affair dating with no strings attached, you should know that is what you really want. Just holding the person you like will fall in love with the fwb partner, which will only make you frustrated in this relationship and make you feel depressed. Because you want more than simple sexual contact, but also spiritual satisfaction, you think you deserve better treatment. Also, you can't get angry because someone confessed their intentions to you, but didn't fall in love with you the way you expect. This is not an exclusive relationship, you don't belong to each other.
You are not a robot. If you send a "Happy Birthday" text message to your FWB, or ask them to have a drink before going home, this relationship will not end. However, if you want to chat with each other every day, or just want to hang out, this will blur the boundaries. When they can't go to the movies with you, you will feel uncomfortable and not valued, or when you are too busy to watch them, they will be upset. Then the feeling is not just casual, but deep into the emotional realm that you haven't even thought of.