I’m sorry to hear of this situation with your wife. Have no idea if it applies here but there is something called “emotional infidelity” which is an intimate relationship of a spouse with someone outside the marriage but there is no physical intimacy. This can happen in different ways but for me it was when I found out my husband was talking frequently about his marriage difficulties with some random woman I didn’t even know. I was absolutely crushed and after the fact my husband was mortified he had hurt me so deeply. Anyway, FWIW men and women can be very territorial and I think that’s a natural thing.