The two phrases/expressions you gave mean two different things.
Frequent Absence(infrequent presence) indicates that something is part of/included in another something, and that it might not always(infrequent presence) be there.
Frequent Absences(!) mean that the inclusion is also absent(optional), so sometimes(!) it is a part of something - but still can be missing. It's double the ambiguity.
In context of the example:
Absence, as someone being someone's husband/wife is a... "permanent" or consistent thing. It is not, and cannot be ambiguous - a clear, binary state, with no transition inbetween.
Yes, frequent absence is acceptable, valid, and clear.
Example Sentence decomposition:
- "It is a love story",
- "About a man with a disorder that causes him to time travel unpredictably"
- "And about his wife, an artist, who has to cope with his frequent absence and dangerous experiences".
So basically, a love story involving husband and wife, where the husband disappears and reappears at times while the wife is like a brooding artist and worries about stuff.
Experiences also took the plural out of absence.
You can only experience one kind of absence - the act of not being there, not have several different experience of the act of not being there.
You can only not be there in one way, not be there. Hence the frequent absence, and the experiences usage. There can be only one word in plural in a sentence, even if it's a loaded, compound, run-on sentence. and that was already given, with experiences. Only, and really the only exception to the rule is when a pluralized word is used as a singular object/entity in a sentence.
To rephrase the example, it would be:
"Tale of a sick, endangered, unpredictably time travelling man, who has a wife that worries about him when he's absent." As in, during his Absence, or frequent absence. Of him not being there. Then being there, after experiencing danger/absence...