How to Decide to Have Sex with Someone
I wish this there was a very simple way to make this decision and all I had to say was, "When you both want to!" Unfortunately, it's really never that simple.
Sex comes with a lot of different expectations and consequences depending on the person. If those things are not communicated honestly beforehand, then things easily get messy, feelings get hurt, or regrets happen. So, before you decide to take that step with someone, consider the following:
Why do you want to have sex with this person?
Are you hoping for something in return (I'm asking this with the assumption you are not a sex worker)? Do you feel like they will owe you something afterwards, perhaps a commitment or a certain behavior you desire from them? Do you just want to have sex because they want to? Ask yourself these questions and make sure the answer to them is "No." All of these questions represent reasons to have sex that are not setting you up for a positive aftermath. They will help you ensure you can have a good emotional response to this person afterwards. Have sex for pleasure or expressing intimacy, anything else may not yield the best results sexually or emotionally.
Has the other person expressed why they want to have sex with you?
Does this person possibly want something from you in return? Are they trying to manipulate you or confuse you in any way? Does this person have a history of such behavior? Also question the timing and whether this person has just been through a breakup or other emotional trauma. The other person's reason for having sex with you may not be what you think it is. Make sure you are aware of this person's reason for wanting to have sex with you and ensure it is a healthy, valid desire.
Have you and this person established the nature of your relationship and what sex would mean?
Is this person one of your platonic friends that you find yourself desiring romantically or sexually? Is this a stranger you would like to have a casual encounter with? Have you been dating this person for a while and want to take the next step? Consider how sex with this person may change the relationship you have with them and whether it would be a positive or negative effect. If there are feelings involved, they should be equal between both parties. If one of you wants to escalate the relationship to sex because they have stronger feelings, but the other just wants to have sex without changing the relationship, that is dangerous territory. Make sure both of you are on the same page about why you are having sex and the type of relationship you want to maintain or possibly develop.
How do you really feel when the time comes?
If you have considered all the reasons why you want to have sex and all the reasons they want to and you're both on the same page about your relationship and the consequences, then the last thing to consider is your gut. What is your gut feeling that comes out in that moment right beforehand? Are you excited? Are you nervous in a good way? Or, do you feel unsure now? Are you having second thoughts and don't know if you're ready? It might not seem like such a good idea by the time it actually gets around to happening, even if you took all the necessary steps to think about it beforehand. Ask yourself how you feel, and if you don't feel excited, good, and ready, then don't proceed, no matter how far in you already are. It's never too late to change your mind.