The visa officers are suspicious of rejected TRV applications, and will check the files. If you applied to go visit your boyfriend, fine. But if the applicant has a long history of trying to get into Canada, a marriage to a Canadian is going to look like a marriage of convenience.
Is this applying to Canada only? My husband has had 3 TRVs rejected; one to Switzerland (he has family there he wanted to visit), one was a TRANSIT visa through London (on our way to Bahamas to get married, which obviously didn't happen), and one to Canada (work and travel visa) for an ESL study course.
I've been a little worried about this subject myself.