If the has lost her colouration this would explain why the male has lost interest, but not why the male ram is hanging around. How long has she had little interest in eating? when did she last spawn? is her belly round and fat or sinking in?
I am thinking a few things...
1. recent spawning and caring for eggs does take it out of fish, if they have bred and raised fry several times as you say, she could just be out of condition and needs a break and building up with some extra foods like brine shrimp in garlic (frozen) bloodworm etc.
2. On the last spawning the male could have got too rough with her during courtship and may have damaged her giving her a bacterial infection.
3 If she is bloated (fat) she could be constipated making her loose colour and having stringy poo (feed a cooked de-shelled pea if this is the case)
4 the stringy faeces is an internal parasite and you would need to treat the whole tank with an anti internal parasitic medication.
Personally I would try 3 first but with her in the breeding trap so you can see any faeces, if it is still white after a pea then treat for internal parasites, once that treatment is done if she has not perked up try the more meaty nice foods see if she perks up any.
Sorry its so vague but it is not easy to give a direct diagnosis in this case, but I hope this helps.
There is a list here of medication that may help.
http
/www.fishforums.net/index.php?/topic/138038-the-a-to-z-of-common-medications/
you should be able to put her back when she is fully healed, dont rush her it sounds like she could have been also exhausted
