This must be incredibly hard for you Whoknows.
I am bisexual, or maybe more pansexual these days I suspect.
However I am also in a conventional straight marriage. I think the key thing is my sexuality is actually a non-issue or red herring maybe because on the day that we married I took a vow of fidelity to him. Not a vow of forsaking all others, except those with the same genitals.
There are marriages/partnerships that do work with consensual extramarital relationships but many of us don't feel that we can accept that. It's not what was signed up to & so I don't think there is an obligation to accede to this purely on the basis that there would be a same sex partner.
Sexuality and monogamy are 2 different things. If you are monogamous by nature then the gender of an extra partner is of no consequence (for me at least). The thing is, what's to be gained here? If it is a case of feeling he can't give you what you deserve & will only be happy in a same sex relationship then that is vastly different to wanting to see if he prefers sex with men.
I can think of a few encounters with women that are 'better' in a way dh isn't able to provide but that is not the sum total of marriage.
I do wonder where he will find himself - many, many people ime can find homosexual porn arousing & may even include that in fantasy but still are very much hetero in real life and would find physically experiencing same sex acts is not for them.
I think I am torn as to how much I feel for him - I can see his need to find out how he feels about this & stop his turmoil but at the same time - you have a sex life together that has been working & he still finds women attractive also so is not finding himself unable to meet that part of your marriage. So...what? Having sex with other people outwith the confines of your vows is an affair regardless of gender. The marriage was otherwise happy - I wonder how much greener grass syndrome is affecting his rationale here.
I hope you get plenty of support - you are an equal partner and while you may not be in control of where he's going you absolutely have the right to decide if you accept it or not.
I will probably be told I don't understand but I think this can be reduced to fidelity or not - and as with other cases you don't have to wait like the condemned, you get to choose too.
I hope the space apart gives you time to process how you feel & what you want to do.