I just came out to my friend as bisexual and he didn't react too badly. However, he asked me "How do you know you are bisexual?". I was totally stumped. I want to explain to him but I don't really know how without going too deep and personal. Is there a relatively simple explanation out there?
Do you think he'll just ask more questions if you just say that you realise you're attracted to both genders ?
You can try something like this: "I am attracted to both men and women. It is just like if you are a straight guy that is attracted to blondes and brunettes, or a straight woman who is attracted to tall and short guys (or any other example/combination that you find useful). It doesn't mean i need both things to be happy, but it means that i can be happy being with one gender or the other."
I've tried that but he just responded with: "But how do you know there is an attraction without dating a girl or a boys"
Just the same way a guy can feel attracted to blondes and brunettes without dating both. Even before a straight guy goes on his first date, he knows (most of the time) which girls he finds attractive or not. It works more or less like that.
You can tell if you're attracted to someone without actually dating them. [They might already be in a relationship, not find you attractive, not looking for a relationship at that moment or anything else that stops you from dating someone even if you like them].
You friend sound like he is in the "selfdinale" stage about you being bi (yes, it does happen even when a person say they are ok whit it). Give him and you some space & time. If he don´t move one step from the dinale after 1 month of thinking for himself and not talking whit him, you may wanna rethink if he can be called a friend. Just my 2 cent, it´s up to you if you wanna use it.
Ask him how, before he'd dated a woman he knew that he was straight. It's the same for everyone, it's just that monosexuals find it easier to doubt us because to them the idea of being attracted to multiple genders seems so foreign.