Languages in Western Europe mainly fall under two Indo-European branches: the Romance Branch, derived from Latin from the Roman Empire, and the Germanic branch, originating in Southern Scandinavia. The main languages in West Europe are Italian, Spanish, French, Portuguese, Romanian, German, and English.
Italy, France, and Spain retained the influence of Latin after the fall of the Roman Empire. The Germanic areas east and north of the Rhine were never fully brought under control of the Romans. The Celts in England weren't strong enough to resist the invading tribes (Angles and Saxons).
Conflicts among languages are usually caused by "ethnic separatism." There have been language conflicts in Great Britain, Ireland, Luxembourg, and Switzerland. There is currently language conflict in Belgium. The Flemish are being oppressed and there is conflict between them and the Walloons.