Don’t you notice how long time couples begin to look alike? Your parents might even look like they’re brother and sister for some reason. No they don’t have to look exactly the same but they have developed this resemblance that you somehow see between them. Here are probably some reasons why long time couples tend to look alike.
(These are all a hypothesis)
Environmental Factors. Couples who live in the same area as each other will more likely experience the same environmental effects the other experiences. For example, if the couple lives in Alaska, then of course both couples with have the same red marks or chills around their faces. The same way as if the couple lives near the beach, then probably they will both get the same tan as the other.
Food factors. Couples are most likely to eat the same food, and overtime, they begin to develop the same physical characteristics the food’s effect may have on them. If the couple both eats meat on a daily basis, then they would have the same figure both on their bodies and faces.
You might want to read: Chillationship: (Chill Relationship)
Emotional Mirroring. This is when you tend to subconsciously copy the usual expressions of your partner resulting to developing the same facial characteristics as them. For example when you marry a person who is always smiling, odds are that you tend to always smile to; and not just smile, but smile the exact same way your partner does. Not because you intentionally copy them but because you subconsciously imitate their expressions and overtime, you’d grow wrinkles and facial muscles on the same parts of their face that THEY do.
So if I were you, date someone who’s really good looking. I’m kidding. Anyway, of course some might say “My parents look nothing alike… blab la bla” This is actually an explanation for those who happened to have looked alike over the years. This doesn't say that all long term couples will look alike.