vanillazoned

When a sexually adventurous person suddenly goes very, very vanilla with a new partner, usually someone they want to have a long term relationship with.The abandoned practices could be non-monogamous stuff like polyamory, or alternative practices like oral, anal, sexting, cosplay, BDSM, roleplay, or other fetishes. Often accompanied by a general reduction in sexual activity. Importantly, it's the formerly adventurous partner, not their mate, who makes this decision.

Depending on the situation, they might think they've grown up, or that sex in long term relationships should be different, or shame in their own kinks, or feeling that their mate is "pure" and they don't want to corrupt them. For many, the real reason is that they have found a partner who they see as a good life partner but secretly aren't all that attracted to sexually. A clear sign of vanillazoning is if after a breakup the partner goes right back to the sexual practices they'd abandoned.

Related to being friendzoned, where implied romance is used to lure someone into a purely platonic friendship. Both concepts have in common the idea that one partner is deceiving the other about the nature of their intimacy in an attempt to secure their preferred relationship type. This is made worse if the kinky partner's kink was what attracted the mate in the first place. Unlike the friendzone, both genders are equally likely to do this.