I’m not sure what exactly you mean by 'chose' to go with a guy?
I think you'll find that if you're hetro this is just teenaged curiosity. Like 80/90% thinking about it in some way in their teens, for some that’s enough, others want to act on their fantasy and try things for themselves.
I don’t feel one curios encounter with another guy labels you homosexual for life. There are a shit load of hetro and hyper hetro guys out there that have had at least one night with their best mate but they would never admit it.
However, if you fancy trying more with this bloke, odds are if you're not bisexual then you may well be homosexual. Sexuality is not all black and white, some people are born with a prominent predisposition to one orientation or the other but some folks are simply flexible.
I can understand the whole guilt thing. In my opinion it's kind of nature clashing with nurture.
Many young men who are homosexual but just don’t understand or realise their sexuality, are still brought up in very heterosexual environment. Some, extremely so, where gays are demonised as foul, evil sinner that cause the worlds ill, while other are just ridiculed as less than 'real men' for being a fag, a poof, a fairy.
We are installed from a very early age that boys kiss girls, boys date girls, score with as many girls as you can, you have to be a stud so women will fall at your feet with their legs open, you have to marry a nice girl, settle down, have 2.4 kids and a dog, that’s what all normal people do, right?
But when, as men, we start to awaked to our sexualities and find it's actually guys we fantasies about and not girls as we were brought up to believe in, I believe for some guys it can causes a massive clash of understanding and leaves you with the worst guilty feeling when you do bang one out thinking of other men.
I sure as hell did and I wish my sexuality had been explained to me when I was younger.
I see a strong coloration between the 5 stages of grief and the acceptance of oneself as gay. It's doesn’t apply to all men, just a hell of a lot.
Stage one, Denial. "This can't be happening to me", I'm not a gay.
Stage two, Anger. "Why me?", feelings of wanting to fight off your homosexuality.
Stage three, Bargaining/Phase/Cure. Dismissing all homosexual feelings as a phase that will pass or if they are strong, that maybe there is a 'cure' out there, some way of bargaining your way straight.
Stage four, Depression. Overwhelming feelings of hopelessness, frustration, bitterness, self pity. Feeling lack of control, feeling numb.
Stage five, Acceptance. There is a difference between resignation and acceptance. One can finally accept their sexuality and sexual express themselves without guilt or remorse because they realise, there is nothing wrong with them, they're just homosexual other than that, we are the same as everyone else.
In my opinion anyways.