Sforno on Exodus 34:15/ספורנו על שמות ל״ד:ט״ו

1פן תכרות ברית, the Torah immediately explains that the reason why entering into contractual relationships with the inhabitants of the land of Canaan is a non starter, is that once you do that the way is open for them to corrupt you by one of two means; either they will woo your sons to marry their daughters or vice versa. It is only the most elementary courtesy then that they invite you to partake in their festive meals (animals offered to their deities) You will not resist such invitations because you do not want to offend the women whom you love. The truth of this was amply demonstrated even with women who did not live in the land of Canaan in Numbers 22,5.