Is it true that bi people, guys in particular, can go thru phases as tho they alternated str8 and gay?

To misquote Alan Cumming, the pendulum swings for some.

In any group there's variety. So you'll find bisexuals that experience this in varying degress, and bisexuals that don't. There aren't many absolutes in human sexuality.

No, what happens with bisexuality is that sometimes we have a crush on a girl, other times it's a guy, etc. We don't normally go through phases and "alternate", we just sometimes have a crush on someone of one gender at one time, then we grow out of that crush and get a crush on someone of the other gender. Simple.

I don't think people stop being who they are based on who they're dating. You may fall in love with a brunette for instance. Doesn't mean you don't think redheads are really hot. I don't think it's a phase. Not when such a large percentage of people who commit suicide are lgbt. When you're "going through a phase" you try to get attention and act like someone you aren't. These people don't want a spotlight. They don't want applause. They just want to love who they love and be themselves without having their rights vetoed by homophobe extremists.

That's what I would tell that answerer.