Though unfortunately named, there's nothing that unfortunate about how handsome ribbed jumpers are, nor how good your girlfriend will look in it when she eventually steals it from you.
The stopgap between a regular wool and chunky cable knit jumper, the 'ribbed' material adds interest and depth, without being so thick that you want to take it off within seconds of walking into your local/the shops/your nan's stifling living room. So, that's good.
But the real strength of ribbed jumpers lies in their versatility, as they go with pretty much everything. However, by all means, feel free to wear one with a white, buttoned-up oxford shirt underneath, some indigo denims and a pair of hefty brown boots. That will look nice. Very nice, indeed.