I agree with pp who say there's no such thing as an emotional "affair".
For me, sexual cheating is a deal breaker. It isn't only the deceit and lies but also the fact that the most intimate and personal act between myself and my partner has also been shared with someone else, while we were supposed to be an exclusive partnership. So no, I can't cope with that.
If someone is sending flirty texts, then that's going to lead to sexual cheating and isn't very different.
Platonic love for someone? That's different. I have several platonic friendships with men, women or couples and I love them all quite deeply, but it isn't sexual in any way. I share emotional stuff, as they do with me, and share strong bonds but they are not ones that would threaten any romantic/sexual relationships they have in their lives.
When I was married, my own husband shared a very strong bond with a female friend. We'd supported a young couple where the husband had died of cancer, leaving a devastated wife. My husband became very close to her and they became friends, but I can assure you he was open about it and there was definitely no sex involved. They spent time together, I do believe he 'loved' her in a platonic way and probably (although I never asked) shared emotional stuff, perhaps he even discussed the state of our marriage or family matters? It didn't bother me, our marriage bonds were very strong and our trust in each other was absolute too.
Eventually my husband supported this woman in finding a new job, she moved away to work in a residential care setting for troubled children. When she left, my husband wanted to give her a goodbye meal, he asked me to cook it as I was a good cook and he was useless in the kitchen! I then went out for the evening with girlfriends and left them to say their goodbyes. It mattered a lot to him, but no, there was still no sex involved.
Over the years this lass eventually met another partner and remarried, and my husband was invited to the wedding.
I think some would not tolerate such closeness with another in a marriage partnership, but we are partners, not jailers. Partnership doesn't exclude closeness with others. While my husband had a special friendship with another woman, it was no different to the special bonds he had with, say, his mother or sister or best mate or whatever. They are all special relationships but didn't impact on the unique bonds we had created in our own marriage.....