Dandere

Dandere (だんデレ) type refers to a character who is often silent and keeps to themselves. It may be due to shyness or just because they’re the quiet type. However, when alone with the person they are attracted to, they usually come out of their shell and become more loving.

This word is a compound of Danmari (だんまり) which means silent and Deredere (デレデレ) which means lovey dovey, but can also be a Dere variant.