I see a lot of people saying things like "some women/men/etc. like it like this", etc. I want to be clear that this isn't about what any specific person likes. Everyone's different. This is about how you figure out what someone likes and whether they are comfortable. And how to do so in a way that avoids actually harassing people who might not be ok with it, are making up their mind and haven't yet, etc.
So how do you figure it out? A few concepts are important: 1) Indicators of interest 2) Indicators of comfort (body language, words, situational things) 3)The person moves ahead on their own 4) Verbal consent. It's important to note that although you should be looking for indicators of interest/comfort, you can also misread them, so it's important that you make use of all these options if need be, not just the first two.
If it's unclear, don't just keep pushing -- clear it up.
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Talking about Inifinitii's story and show how these things apply:
If somebody says "Do you want to go to a hotel?/Let's go to my room" and the other person says "Well, I'm actually more into X than men" (you can adjust this for the genders involved) that is not enthusiastic consent. Nor is that comfort. If they are giving excuses "Well, my mom is tracking my location on her cell phone" etc., that's not comfort or consent. Lots of people give excuses when they're unsure or feel uncomfortable and don't want to hurt your feelings directly. It's important to note that just because the person doesn't flat-out send you packing, doesn't mean it's cool to keep begging or pushing them, or repeating some action until you think they'll give in and do what you want them to. They may be enjoying hanging out with you and not want to kill the vibe, but also not want to go further in that moment. Emotions are complex.
If you're in a position of power (you're significantly older than they are, you have seniority over them in an organization or job, they look up to you, you're a known personality and they're a fan, etc) or you're in a situation where they might feel unsafe (they are outnumbered by the gender they're interested in, they are alone, etc) then you need to make doubly sure. You can never be careful enough in those situations because it's so easy to mistake influence for interest.
If you're in an intimate situation and you take someone's hand to do something and they pull it back, that's a sign that you need to chill out and reassess. If you get an indicator of discomfort, even if it's not a hard 'no', you should hit the brakes and verify together. 'No' is not the only sign of discomfort. Someone turning away, pulling their hand/arm/etc back, flinching in an uncomfortable way can be indicators of discomfort. Their facial expression or their voice can be, as well. If you're not sure, ask them how they're feeling. I don't mean some long, awkward, complicated speech.. Just be confident and direct. It takes 2 seconds to ask somebody "Are you cool with this/is this ok?" or "Should we slow down?" and it can save you from making some very bad mistakes.
Key concept 1: Consent is a staged process. It's not like everyone who meets you, even if they like you, is giving you consent to everything just because they consented to a first step (or a second step, etc). At every step of the process, it's your job to figure out 1) How comfortable your partner is, and 2) Whether they're ok with going to the next step, or not.
Key concept 2: If you want to avoid people feeling harassed, you need need to either clear things up directly when you're unsure, or just take a rain check and wait until you're in a situation where it's more obvious and you are sure. 'She/he might have liked it' is not good enough after the fact once the damage is done. If it's too murky, it's way better to ask or just chill out than to roll the dice on leaving someone with an experience that could take them years to recover from.
For indicators of comfort, if you want to avoid screwing this up, it's important to look for enthusiastic answers. "No" then "no" then "no" then "Well, maybe ok" is not an enthusiastic answer. Not getting a "no" is not an enthusiastic answer by itself.. Sometimes people need time to figure things out. Sometimes people are afraid to say how they feel. If you take these as consent you're rolling the dice and in danger of hurting someone. If they're just neutral and you can't tell if they're enjoying your advances, then clarify it, don't just assume.
Never beg someone for or push someone into sex, sexual actions, or to do something they're not expressing that they're comfortable doing. The fact that you eventually get them to do it doesn't mean they felt comfortable with it or were ok with the whole thing. If you ask or suggest and you're getting no enthusiasm back or neutrality only, slow down and make that person feel more comfortable, and pay attention to the signs they give you back. It's perfectly ok to be patient in order to verify that someone is ok. Rushing leads to mistakes and regrets.
Whatever people tell you, I've not been in a single situation where someone who was excited and wanted to move forward was discouraged simply because they were asked if it was cool. It hasn't stopped me from being able to enjoy finding and meeting mates. It's always worth taking the time to figure it out when need be. This doesn't mean you need to be afraid of talking to people you're interested in or taking things to the next level with someone who's interested in you. It just means that you need to be patient, aware, and careful when you do. This is how we can all do a better job of making each other feel comfortable and protecting each other.