i agree about the evaluation. i might also consider therapy. either support for myself or family therapy/couples therapy with your husband so that in these two parts of the so-called triangle there was confidence,clear communication, and a common way of understanding and addressing the situation.
some thoughts:
6 years old he is not developmentally capable of being in love like a husband.
masturbating can start way before this and be normal. the question is if there was an event or interactions that overstimulated him or made him highly anxious. curiosity about bodies, same and opposite sex, too,is normal', i believe. but same thing. unless a child was overstimulated in a a way he could not handle.
all of us when something goes wrong with our child shine the spotlight of guilt on ourselves. let me stand first in line to tell you it does not help.
your husband seems to be playing a role in fanning the flames of concern by his reactions. son is his son. not a rival.
the gazing at you is complex. children are profoundly attached to their primary caretakers. the gazing of infants to a mother's face is a singular way that a child's identity is consolidated it is also a way to get reassurance when anxious. if you watch children and adults, we continue to gaze at beloveds, whether they are our mates, children, mothers or friends.
to me there is no specific behavior of your son that seems overly concerning in itself. the so called family romance or oedipal complex is thought by many to be universal.
but if there is anxiety and jealousy or rivalry, fear, shame, anger or suspicion by any or all of the 3 of you, this could contribute to concerns.
i can only imagine how nervous and concerned you must be by the sense your marriage is affected by this. that is where i might start first. i would get the help of professionals.
i hope you keep posting. it helps.
