How Sexual fluidity works? Can a heterosexual male that doesn't have any attraction towards male become gay without any attraction towards females.
Or will he become bisexual because he was heterosexual before.
Sexuality is thought to be mostly fixed (and certainly does not respond to active interventions to change it), but sometimes self-descriptions shift. It's unclear to what extent these shifts are changes in sexuality itself versus changes in how people identify. More broadly speaking, people aren't always good at describing their own wants/desires/feelings, and social and cultural factors can have a strong influence. Individuals may have experiences that make them rethink how they see themselves, or they may be more or less comfortable expressing a view that is outside perceived norms at different times.
Savin-Williams et al 2012 studied a group of young adults longitudinally and compared self-reported sexual orientation during two study waves, one when participants were 18-24 and later when they were 24-34.
Out of 5204 men who reported being &quot;100% heterosexual&quot; in the first wave, the vast majority, 5064, said the same in the second wave. 105 said &quot;mostly heterosexual&quot;, 11 said &quot;bisexual&quot;, 24 said &quot;homosexual&quot;. Other categories were somewhat more fluid, as was sexuality among women, and you can see the whole study linked below.

Savin-Williams, R. C., Joyner, K., &amp; Rieger, G. (2012). Prevalence and stability of self-reported sexual orientation identity during young adulthood. Archives of sexual behavior, 41(1), 103-110.