He married her because she was orphan, otherwise noone would take care of her. If course nowadays this makes no sense, but this was 1400 years ago He didn't have intercourse with her.

Ir you want to know what Moses, the Israeli leader, did just open Old Testament on Deuteronomy 20 and Exodus. Sneak preview:

-he killed 3000 of his own people for adoring a cow
-commited genocide and erase the Caanites out of the map (Caanites lives in Israel before Moses people)
-said that anyone working on Saturday should be killed
Etc

Just read Deuteronomy and Exous to know how Moses people act