What are the main reasons Ireland has had trouble relationship with great Britain?

Answer 1

Partly because they preferred to be Irish and partly because of religious differences.

Ireland was mainly Catholic and England was protestant.

Before Irish independence there were several laws descriminating against Catholicism and against Irish nationals in favour of the occupying English.

Now Ireland (Eire) is a Catholic nation and Northern Ireland is largely protestant. Continuing troubles in the North still arise from religious differences.

Answer 2

Many Irish have felt oppressed by the eight hundered years of British occupation, and even today some loathe the fact that Northern Ireland is under Great Britians domain. Also the fact that the two had previously been at war with each other on multiple occassions had something to do with it. Another way is the preception of the Irish in Great Britain. Many saw the Irish as a source of cheap labor and working class british therefore felt that Irish immigrants to Britain were a threat.