Gourami changing colour and may be building nest

[DJMdevon]

I have a male and female dwarf Gourami in a 110l tank. The male has recently partially changed colour from a pinky colour all over with stripes to having a blue stripe underneath and along part of his fin (pic attached of his change in colour). He is also being very aggressive toward his female companion chasing her up and down the tank, sometimes chasing her into the glass.
Ive been thinking about separating them or possibly re-homing (as they decimate numerous plants) but noticed this morning that the male appears to be building a nest using bits of shredded plants (pic attached).
Should I leave them for now? Any suggestions?
Thanks