One approach to consider may be to gain common law status by living together continuously for one year. May not be possible in Canada, but perhaps in Nigeria. I think that would resolve some red flags in a better way than marrying.
Hmmmm.... even if I took a leave of absence from work and we stayed together in Lagos for a while that could help. Ironically, Nigeria is super strict in granting Visa's even to Canadians! I'll have to look into it.