Apart from adding extra text, like 'She emphasised the word "use"', which is horribly clunky, I can't think of any better method than using italics. That's what I do myself, but I think it's important to do so sparingly.
As to whether it's necessary, there are certainly many cases when it can be. In dialogue we rely on emphasis to convey the meaning. So somebody saying
Just put the green plastic rings on the table |
|
could indicate
Just put them there - don't stick them
Use only the green ones
Use only the plastic ones
Use only the rings, not the cubes
Put them only on the table, not on the floor
Without the use of italics there's no way of knowing which meaning was intended. Probably it needs to be reserved for this type of sentence ( a silly example, I know) where the absence of emphasis either loses the meaning or causes confusion. Either that or write the sentence differently!
Chris
<Added>P S Meant to say - in your example, I reckon you could get away without the italics because you have already highlighted the importance of 'use' and 'affection' by having the characters query them just before the sentences in which they are emphasised. C.