Why am I behaving like this ?

I am all fine, being single and alone but not lonely, I work and like my own company too much that I do not want any guy or neither do I want to spend my life with anyone. Perfectly fine on my own, working, shopping and I love animals. I am a landlord too so I rent out rooms to male tenants. I had rented out to many male tenants but only this particular tenant got me, I am fine with other tenants has gf to Wife but I do not get jealous or something, even if I see living couple outside, I also don’t care much but this particular male tenant got me, ok, he is tall, slim and always give me those big wide smile, he talks alot too. When I found out he has a gf and talks to the gal every night for hours and mind you, he always put on speaker and I can hear. Why must he let me hear the gal ‘s voice, seeing them so loving , I can’t help but feel jealous and start to wonder, do I really need a be? But I don’t want to, he is messing up my head and I can’t even breathe well with him staying in my house. I felt jealous too but other guy tenant don’t make me this way?