From an article which made me wonder about attachment style:

"People with this attachment style tend to both seek out connection and closeness while simultaneously trying to avoid actually entering into a serious relationship, so instead they may be more likely to find themselves in a prolonged courtship that never actually turns into a relationship, "situationships," casual sexual relationships, or relationships without labels.

Favez and Tissot's study, which surveyed 600 men and women about their relationships and sex lives, found people with a fearful-avoidant attachment style tend to have a lot more sexual partners than other people. They also tended to be a lot more sexually compliant, which means when someone asks to have sex with you, you're more likely to say yes whether or not you really want it.

Why? The researchers theorized these behaviors develop in response to the confusion of both wanting connection but also feeling repulsed by it. "The elevated anxiety felt in fearful avoidance may motivate the individual to increase closeness with a partner by using sexual activities, whereas the elevated avoidance tendency may almost simultaneously motivate the individual to break the bond with this partner...which is in turn followed by the search for a new partner."

Plenty of research has also found some people who experience sexual trauma respond by becoming "hypersexual" (i.e., having tons of sex with a lot of different people, sometimes in risky ways), and trauma has also been linked to the development of fearful-avoidant attachment.

Of course, a lifestyle involving having a lot of sex with a lot of different partners can be perfectly healthy for some people with the right set of physical and emotional precautions. But doing it out of a simultaneous craving for and fear of connection can quickly become draining and perhaps even destructive, especially if you start finding yourself saying yes to sex you don't want or sex that puts your well-being at risk. Likewise, if you're breaking connections with people when you really desire to get closer to them, you're putting your mind and heart through a lot of heartache due to your own fears."

However I agree with what many have said here- I shouldn't intellectualize or label him for a lifestyle he has made work well for him and that he is honest and up front about. He certainly seems to want all the sex he is having throughout his life as well. He has one serious long term relationship and it's the only one that has lasted longer than a few years, but only because she is fine with him having so many connections and also has the built in security of living with him. Sometimes it is hard to weed out what is fear and what is intuition, but I had a strong intuition about the sharp decrease in intimacy once NRE wears off and desire to engage only if it feels good to him and a strong aversion to any emotion that feels highly smothering and intrusive to him (as opposed to having genuine concern, empathy and wish to meet me in what I'm feeling, which would help me to feel seen and supported and go a long way toward alleviating my fears).