How can I avoid becoming less invested emotionally with girls I meet?

[Zzupforadventurez]

When I meet an attractive and intelligent woman who enjoys similar interests as me, we tend to get along quite well, at least considering these women often take the initiative to call me to participate in activities with no other participants. However, eventually I seem to become emotionally invested and although I try to keep things platonic, I invariably develop feelings. Despite trying to hide them, eventually it becomes apparent and then things become platonic for real, based on the withdrawing of affection from the women. What can I do to prevent this from happening in the future?