Freezing is a must with fatty acid supplements. In Biochemistry (upper division university), we were tested on this. I don't want to go into details, but basically say that fatty acid supplements should always be frozen or refridgerated to maintain quality. The molecule stays more active and biologically useful. The nutrition stores that are serious and in-the-know will always keep fatty acids refridgerated.
I haven't read anything credible about libido, but studies have shown that Fish Oil supplementation improves sperm motility.