I am assuming they were a chosen pair. They did not show any aggression to each other. That night when I turned off the lights, the two fish were in one spot together all night. Before the "female" died, they were split up with "him" on one side and "her" on the other. The remaining fish ate the night the other one died.
I don't know your level of experience with fish, or with cichlids, so pardon my assumptions. I would know within a few minutes if the cichlids were both male, both female, or a pair, solely from how they interact; and I would also have a fair idea of whether or not they had or were likely to bond, though this latter aspect can take several days if not weeks of careful observation for long periods (so the fish do not know you are still there--they rarely act "normal" if you are because your presence distracts them (you are associated with food, or perhaps possible danger, and fish behaviour will be very different at such times). Not much more I can offer, the fish may have died from internal injuries during netting/transport, or something genetic, or stress, or aggression by the other cichlid. I would certainly not advise you getting another ram, the sole survivor will be fine on its own. This species is believed to live largely isolated except when spawning.
As for which tank...the 29g is necessary before very long. That brings us to the other fish already there, and you have some issues.
Nick mentioned kuhlii loaches needing a group, what we term a shoaling species, and the white clouds and black neons are also shoaling. The five WC are OK at this stage, but I wold get another 4-5 black neons for a total of 7-8 if you like this species. That means, if you decide to re-home some fish, and these happen to be a species you are not now fond of, there would be no point in getting more but instead trying to re-home the three. The black neons are fine with the ram, the WC are not. I would re-home the WC as they need no heat (room temp is adequate) but the ram will not last without some warmth (76-77F). WC also like more water current than rams, or neons come to that, so there is another non-compatible issue.
The pea puffer (dwarf puffer presumably) should be alone, certainly not with rams or neons or WC. A 10g is fine, planted. [You mention snails, that is not a problem as they eat all organics and allow bacteria to break it down faster.]
Once you can ID the "algae eater," you may need to re-home it. Most of these get large, 5-6 inches, and they can become quite nasty as they mature. The Chinese Algae Eater is known to sometimes eat the slime coat of fish. It is in any case too large for a 29g. As it matures, it eats les and less algae but makes quite a mess, aside from the temperament.