He strives (present)
He strove (in the past and has possibly stopped striving)
He has striven (in the past and is possibly still striving)
Never "he strived" without the "has" (false and ungrammatical past tense - but hey ho, false and ungrammatical constructions are proliferating, so it could be the definitive past tense this time next year)
A quote for those blessed with a spouse:
I hope the new PM is kind to Larry the Cat




