jealousy and insecurities

my man is a really good boyfriend and he makes me happy but sometimes i just could not help but feel insecure and jealous whenever he would hang out with his friends since most of his friends are female and he has already explained me that its just that majority of his classmates are female. I just feel bad for feeling this way since my man hasn’t done anything wrong or overstepped any boundaries in our relationship. and whenever he would hang out w his friends he would send me pics from time to time even if i didn’t ask for them which i really appreciate. i’ve already told my man my insecurities and jealousy about his friends and he has never failed to reassure me.. i just really feel bad for feeling this way because sometimes i would just suddenly get upset w him because of this matter but i would not tell me since i didn’t want to seem controlling about who he should hang out with