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if your question is, ''How do I get a Euryops to rebloom?'',https://www.gardeningknowhow.com/ornamental/shrubs/african-bush-daisy/growing-bush-daisies.htm
The following article should answer bougainvillea questions: https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-in-containers.htm

If the previous plant looked bad or died, then it was likely suffering from a disease or other issue. Therefore, it is highly probable that anything planted in the same area could suffer the same demise if left untreated. Here is more information: https://www.gardeningknowhow.com/plant-problems/environmental/planting-in-old-spaces.htm It could also be from transplant shock, which normally fixes itself once established. I would keep a watch on it. Ensure that it's not too wet. Check for pests, and if need be just to be on the safe side, treat with fungicide - like neem oil.

The first thing to do is to move your plant - it needs full sun, and growing under the shade of a tree is going to weaken it and leave it open to attack from various bugs and disease. Read this article about bush daisies: https://www.gardeningknowhow.com/ornamental/shrubs/african-bush-daisy/growing-bush-daisies.htm.
You can take some samples of leaves and flowers to the Extension Service to find out the best treatment for the attackers, also the names of good plants to use beneath the pine. This link will help you locate the nearest service office: https://www.gardeningknowhow.com/extension-search/

Container plantings need daily water and even twice a day during heat above 85 degrees F.
Make sure the soil is moist but not soggy.
Root rot could also cause the flowers to not open.

This article will refresh you on the care requirements.
https://www.gardeningknowhow.com/ornamental/shrubs/african-bush-daisy/growing-bush-daisies.htm

No, in fact, it looks like the amounts of water are just a little too much! It looks to have contracted a fungal infection.

You will need to correct with a fungicide. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm

That will be overwatering. These plants are adapted to the heat and dry. They originate in Africa in hotter, drier regions.

They will not need much extra care, as long as doesn't freeze for very long in your area.

This article will help you to care for them: https://www.gardeningknowhow.com/ornamental/shrubs/african-bush-daisy/growing-bush-daisies.htm