"Strike" means to hit something. The phrase "strike a note" is a musical metaphor. You "strike" the keys of a piano, or the strings of a guitar to produce a "note". Did you strike the proper note? Did it sound beautiful? Or did you strike the wrong note, and does it sound terrible? This is how we use the phrase "strike a note" literally. If we want to use it metaphorically we can apply it to all kinds of different situations. "It might make it hard to strike A REALLY ROMANTIC note." When we form a sentence like this we are no longer talking about pianos and guitars. Instead we are talking about the things we do and say when we're trying to be romantic. Now here is a question. Do you think it's romantic to wear a T-shirt on a date? Or do you think it's a little bit wrong, like striking the wrong key on a piano?

Perhaps academics could answer instead of comment.

Stinking of onions, wearing your dirty overalls, or going without bathing are all examples of what might make 'it' hard to strike a date, for instance. Turning up in your best suit with a bunch of flowers would make it easier to strike a date. Strike is a verb used in sport, strike the ball; also in Madonna's infamous line of 'strikeca pose.