Help me figure out my problem

I am a very clean person. I know it is natural for yeast to come out of you. But I don’t understand why it comes out as often as it does. I think it’s. Yeast infection. I’ve treated it before but it just keeps coming back. It normally happens after my fiancé and I have sex. Does that mean he could have a yeast infection? It is itchy at times, yes but not like usual. Also, he thinks that I’m cheating on him. When I know I’m not and wouldn’t do that. Help me please figure out how to get rid of this. Also, i have never douched so I don’t know how that would work. Please help... thank you! Have a good day!