You've put several variables on the table for us to look at, but you haven't explained them enough to understand you. What intelligent advice could we possibly provide?
For instance, your first marriage sounds like the bisexual dream: you both identified as bi, neither of you were jealous of outside same-sex trysts, and you say the marriage was happy. Yet it ended in divorce, then you apparently jumped right onto the very next woman you encountered who said she doesn't mind if you sleep with guys on the side. There's a missing piece between these two events: if your first marriage was "happy" why did you break up? Thats a very important element needed for anyone to venture an opinion of your current dilemma.
Myself, I can only tell you what I've learned from the bisexual men I know as friends. Each has said their bi attraction is fluid, and shifts as time passes and they get involved with different partners. But at bedrock, some have an instinctive primary attraction to one sex or the other: that gender is the one that gets their rocks off with no fuss and no second thoughts. The guys with primary attraction to women are usually in reasonably happy long term marriages, esp if they are older (40+). The ones who are more attracted to men struggle a bit more in their long term hetero relationships, for reasons too varied to go into here. Much depends on his level of emotional attachment to the woman, if they have children, how that woman perceives the relationship, whether her particular needs are met, and to what degree he acts on his attraction to men (not at all, with trysts, or regular partners). I don't personally know any bi men involved with bi women: they'll all with hetero women.
How long have you been with your current wife? If a couple years, you may just be in the typical lull that happens in most hetero relationships. Men get bored, even if they adore their wives. Attraction ebbs and flows, on one side or the other. Problems like finances or family or job stress can also throw a couple out of sync sexually. Often these things self-correct with a little time, and attraction returns.
Do you have any male partners aside from this rocker dude? If not, and he has limited availability due to frequent travel, he will ALWAYS seem way hotter to you than anyone else: thats just human nature. We most want what we can't control. Since you've known him so long, its also possible you've unexpectedly fallen in love with him over time. Perhaps you love your current wife, but suddenly find you're "in love" with him. Maybe you yourself started out genuinely bi, but have recently drifted toward more distinctly gay orientation. Or, and forgive me here, but you might just be a selfish dick who doesn't really know WHAT he wants but pulls unwitting partners into his orbit anyway. Being a dick has nothing to do with being bi: anyone can be a dick (men, women, gay, hetero, bi). I've been a dick sometimes: we all have.
See? Your questions have many potential answers. Unless you give more specifics about these people you're involved with, and exactly what they mean to you, all anyone can do is guess. If I were you, I might consider seeing a therapist for a session or two, to sort out my thoughts and feelings. The two marriages in quick succession may indicate an unresolved issue you aren't fully aware of.
