I recently got a yeast infection about 2 days ago And my partner thinks I have had other partners because of this but I havent.?

You are "right" There is no correlation between yeast infections and an additional partner since yeast infections can be caused by antibiotics, douches, etc. What is of greater concern is why your partner is so quick to express that concern when you clearly said "it isn't so". This relationship has some "communication issues" that need to be addressed to maintain a level of "intimacy". or not.