could this indicate cheating?

i notice that on some mths, my husband only wants sex 1-2x a mth, while others, he wants it 2-3x a week. like oct 2017, we had it 2-3x a week. nov 2017, we only had it 2x that whole mth. dec 2017, once the whole mth. jan 2018, once a week. then on feb, 2-3x a week. march is back to 2x a mth. i feel like the time when he wants it a lot, he cheated on me. while the times he wants it less he goes to porn. what do u guys think?