Hi and welcome.
The simple answer might just be that she can’t ejaculate from G Spot stimulation. Generally to do it from G Spot stimulation, she needs to orgasm from the stimulation and not everyone does. The alternative answer is that she can but maybe doesn’t ejaculate enough fluid to be noticeable and/or she isn’t actually expelling the fluid. The latter could be due to her body not pushing it out or it could be due to the toy or your hands blocking the passage. Does she get a sort of sloshing noise during G Spot stimulation? If yes, then that is the fluid she may just need the orgasm or stronger kegel muscles to help expel the fluid or to get the toy out quicker.
Please don’t take this the wrong way, but it is worth double checking that you/her are in the right place. The G Spot is normally between 1 and 2 inches on the front wall of the vagina, although it can vary a bit. It is easier to find when she is aroused as it will engorge.
Why not try combining G Spot stimulation with other stimulation. Clitoral is the obvious answer but anywhere she likes to be touched, kissed etc. Make sure she is distracted enough with the pleasure to not be focusing on ejaculating/orgasm etc. Over thinking will stop it happening. The first time I ejaculated was from a wand on my clitoris and a metal toy being used on my G Spot.
In terms of possible toy recommendations, metal toys will give the firmest pressure. Glass is good but does lack the weight. I have recently bought this glass tentacle . I haven’t much of a chance to use it properly but I really do like the shape as you can use either side to either cup or press against the G Spot. There is a similar ish design in metal but I can’t comment on it as I don’t own it.
It may just be a case of experimenting with material, size and shape to get the best pleasure for her. Maybe something that fills her more so that something will be rubbing against her G Spot without it having to be the tip of the toy. Or something with a bit of a wider, flatter tip. Generally I prefer toys that have a realistic/semi realistic penis head rather than something too bulbed. I do find internal vibration a bit hit and miss, but personally find rumbly vibrations are the only ones that standard a chance of working.
The other alternatives would be to look for toys with internal movement. This could be something like a come hither motion, the obvious examples being the Lelo Wave toys or more of a thrusting toy like the Fun Factory Stronic . Toys can achieve a perfect rhythm that is humans just can’t emulate, which might help.
Alternatively, there are toys which have moving balls or tapping sensation. Off the top of my head I’m not sure what Lovehoney have so you’ll have to have a look. The only one I can recommend is the Fun Factory Sundaze which has the same thrusting function as the Stronic but also a series of tapping and other settings. I will say this is not a fast orgasm toy and does take a little getting used to in terms of the settings but if more traditional toys aren’t working, it might be worth looking at.
Otherwise, there are plenty of rabbits that have movement internally. It can be a little difficult to find the right rabbit that will line up with your wife’s anatomy, so don’t be disheartened if the first one you buy doesn’t do exactly what you want. I would recommend one that has dual controls so you can control the internal and external arms separately otherwise often the clitoral sensations do tend to take over.
Whatever you chose to do, focus on the pleasure and the enjoyment of being sexually intimate together. Exploring and wanting to try new things is good, but sex shouldn’t be about unlocking achievements. Picking up a toy with the mentality of “let’s see if this one works then” will almost guarantee a failure and the word “failure” really shouldn’t be used in relation to sex.
It has crossed my mind.