A bit of an old article but showed up in, of all things, my Facebook feed recently (I am always astonished when good things show up on my feed; I suppose that means I have good friends).
What does it mean to be gendered? Is a sexual orientation a lifestyle?
I never really understood monosexual people and I'm becoming increasingly convinced that they don't understand themselves. I'm all for identifying however you want, but maybe reconsider your worldview or self image if you're identifying with something so explicitly contrary to what you're doing. Or at least don't act like confusion is unwarranted.
As for your questions, Sexual orientation is not a lifestyle but society makes it difficult to not accommodate a minority sexuality with lifestyle choices. The sheer volume of repulsive behavior and aggression queer people are subjected to by cishets makes it an easy choice to only associate with other queer people. Of course this isn't always possible, and it becomes harder the more visibly nonconforming you are. Gender is a construct. So are traffic lights. If you ignore either of them, you get hit by cars. Which, also, are constructs.
Personally I do not think sexual orientation is a lifestyle but more of something that you're born with. For example I'm going to use a tumblr post I have seen recently. So Orange is the New Black had its new season recently released and Ruby Rose is now a part of the cast. The post would say something along the lines of "If you're a straight girl and you just watched the new OITNB, I've got some news for you. Ruby Rose just turned you into a lesbian."
This just makes it seem as if being gay is a choice that you can change into for personal convenience. It really diminishes the actual issues that the lgbtqia+ community faces when it comes to people telling them that they are choosing to be a special snowflake. If they wanted their lives to be easier they would not choose to identify as something that will get them ridiculed, fired from their job, not marry (until recently), be denied service at a business establishment, and in some cases beat up and killed. So when people say that being queer is a life choice it really turns me the wrong way.