Assalaamu 'alaykum sister.
I read your thread and I wanted to say that don't let it upset you. People leave Islam for various reasons. Some people even enter Islam for the wrong reasons, e.g. they may like someone and become Muslim just for them and when they break-up then they leave Islam. Some people only learn about the basics, such as tawheed, the pillars of Islam, eemaan etc. and of course these make sense, a perfect way of life. But then when they start to learn more, they find out that e.g. it's not permitted for them to drink alcohol, they have to eat halaal, they can no longer freemix, they can't own a dog, can't celebrate christmas, can't listen to music etc. And so they may find it too much and maybe they were not sort of expecting to follow so much guidelines, if you know what I mean. They may feel as though it's too burdening for them and they won't be able to cope, and so they leave Islam.