Australian Tourist visa rejected

My Fiance had been in Australian on a tourist visa for 3 times now since 2016. He always return to his country before his visa expires. 4th time he applied it was rejected for the reason that they think he won’t stay in Australia temporarily. We always submit same requirements as we did before but cannot understand why his application was rejected. Here is the part of the letter from embassy...

The applicant is currently self-employed and have provided no evidence of ongoing work commitments and income. Having considered the information, I find that the applicant has failed to demonstrate that he has significant economic ties to the [country of origin] that would induce him to return home within the validity of the visa. I have considered the offer of support provided by his relative in Australia. Generally, however, offers of support or guarantees given by family and friends in Australia are not sufficient evidence of a genuine temporary stay. The onus is on the applicant to satisfy the decision maker that the applicant intends only to stay temporarily in Australia.

I am not satisfied that the applicant’s personal circumstances support his claims that he intends to temporarily stay in Australia as a visitor. Therefore, I find that he does not meet clause 600.211.

Decision

As the applicant does not meet clause 600.211(c), I find that you do not meet the criteria for the grant of a VISITOR (Class FA) VISITOR (Subclass 600) visa. Therefore, I refuse your application for a VISITOR (Class FA) VISITOR (Subclass 600) visa lodged at [embassy/consulate].