Should they not expect too much? I’m so confused!

My sister and her bf have really bad Uranus aspects and Im worried that it wouldnt be stable enough, cause my sister is deciding to marry him but I doubt that will be possible or if they do their will be a sudden divorce ahhh Im worried for her what do I do? They barely have any Saturn contacts in synastry but they do in the composite even though they are hard ones. In the synastry though they have like double whammy Saturn/Uranus (Saturn conjunct Uranus and Saturn sesquadraite Uranus). Then they have Uranus conjunct sun and venus to make things worse.

I’m worried should I tell her not to expect too much?
But then again I don’t want to crush her dream but then I don’t want to see her hurt either! So confusing!