I know that women are more or well lubricated than men. But am wondering, is the woman's fluid prompted by her being aroused? Or is the fluid still there whether she is aroused or not? I know this fluid helps sperms to swim inside and that's why I wonder, if the fluid is not there, are chances of implantation still high?

A woman's vagina is always moist.
It just becomes more so when aroused.

If there is no fluid there sex would be very painful so I guess implantation would be low as sex wouldn't happen :confused:

If HE ejaculates, you can still get pregnant. Period.

MANY women need to have lubricants besides their own natural lubrication--there are many reasons unrelated to arousal involved there.

Lubrication is still present in the vagina, and is much more when she is aroused.
No matter if she is lubricated or not, if you have sex with her, and do not use birth control, she CAN become pregnant. Use protection.