I'm reading this sentence in my head because I'm in the library. I can't read it out loud. Does this sound right to you? I'm not sure?
According to the theories on mate selection, researchers have developed the idea that most people select their mates according to the factors they have most in common with.
It's fine -- except you can omit the last word -- "with." Technically, we shouldn't end sentences with a preposition. In this case, "with" isn't even necessary.
okay, thank you!
You're welcome.
Do I need to add a comma before the and in this sentence?
The second most frequent reason is that the couple falls out of love during the relationship and they no longer feel connected or willing to put the effort to make their marriage work
Other reasons why a relationship ends in divorce is the lack of good communication skills the couples use during conflict situations.
How's the sentence structure on this one?
Good communication skills also improve the quality of intimacy in the relationship as well as an increase in self-confidence.
A comma after "relationship" would be a good idea, yes.
It would be more accurate to write this:
Other reasons why a relationship ends in divorce is the lack of communication skills, expecially for use during conflicts.
Need for parallel structure here:
Good communication skills also improve the quality of intimacy in the relationship, as well as the couple's self-confidence.
You have two elements here that need to be parallel -- the two main ideas after the verb:
~quality ... (noun)
~... self-confidence ...(noun)
It's logical to "improve the quality..." but it's not logical to "improve ... an increase..."
Do you see?
Sorry -- the beginning of that sentence should read this way:
Another reason why ...
(The verb is singular and you name only one element after that.)
Also, be sure to correct the spelling of "especially"!!