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

[ekfishlover2011]

1. That stripe means he is wanting to breed.

2. Chasing could mean wanting to breed or that she isnt a suitable mate for him. Either or, hard to tell.

3. Thats not a gourami nest. They make bubblenests, nothing but bubbles. I dont know what hes supposed to be doing there.

4. I suggest separating because in that small of a tank if they get really aggressive there is nowhere to run. Even in my 75gal when my female told the male no and he didnt listen she was able to corner him and beat him to a pulp and they killed eachother and injured my Peacemaker fish as well.