Does groping in the dark have negative (sexual) connotations?
Solution 1:
"Groping in the dark" is a long-established idiom for "aimlessly grasping for something", literally or figuratively. It could be used (with a wink) to imply something sexual, or it could be misinterpreted by someone not familiar with the vernacular to imply something sexual, but it is not (in the US, at least) a term one must avoid in general writing or speaking, where context might not imply a sexual meaning. After all, probably about 20% of English words might be used with a sexual connotation.
Solution 2:
Groping someone (no preposition) can have a sexual meaning; it generally implies unwanted sexual touching. However, we can innocently grope, in literal or figurative darkness, for a sought thing, solution, answer, pathway, etc.