Do guys feel jealous whenever their girls are becoming close to their male friends?

My boyfriend is one person that never speaks out... You can only tell if something is bothering him through his actions... So his the one that introduced me to his Best friend and told me to be free with him and treat him accordingly coz he considers him as his brother... Now his friend and i have really built a close friendship (sister and brotherly friendship).. But now what am noticing from my boyfriend is him being distant, he communicates less and his just showing some rebellious behavior. His friend tried to reason with him with his behavior towards me. Right now his coming back to his senses little by little... Could it be that his jealous of my friendship with his friend but just can't express it by mouth?
Do guys feel jealous whenever their girls are becoming close to their male friends?
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