Can you help me

Last Sunday when I went to my friends instagram page I saw that she put 🏳️‍🌈 in her Instagram bio but she’s engaged to a man. on Sunday I was at work and I saw her friend but I don’t think he knows me. But when I went to her Instagram page at night I saw that she put the 🏳️‍🌈 on her Instagram bio. I thought she put that flag there for someone to let them know she’s bisexual. Or she just put it there just because? Sorry haha just curious